Kalshi's market on Wednesday's US Open men's singles quarterfinal between Karen Khachanov and Alexander Blockx has settled: Khachanov won 6-2, 7-5, 3-2 when Blockx retired in the third set on Wednesday evening, and the Khachanov contract paid $1 at 6:49 p.m. ET while the Blockx contract paid nothing. The price that paid it was quoted at 58¢ bid, 59¢ ask, with Blockx at 41¢ bid, 42¢ ask, as of September 8, 2026, at 6:02 a.m. ET, and that pull is what this page was written on. Read as probabilities at the time, the 30-year-old Russian, ranked No. 50 and unseeded, was a 58 to 59 percent favorite over the 21-year-old Belgian who was seeded 28th and who told reporters after Monday's win that he had been "really close to retiring" with a rib injury. That last clause was the whole market, and an injury, if not that one alone, turned out to be the whole match. Of Wednesday's two quarterfinals, the other one had Alexander Zverev at 87¢ to 88¢ against Botic van de Zandschulp, so this was the match the market could not call, and the reason had less to do with tennis than with a rib nobody outside Blockx's camp could see.
The price did not start here. It opened Monday night at 80¢ into an empty book, got sold down to 54¢ inside an hour, and found 55 to 57 by 11 p.m. ET. The net of every cent since has been bought: the crowd took more than 16,000 contracts of Khachanov in eight hours, and the price moved two cents. Where the buying stopped is written on the order book in a number I will get to, and it said Wednesday's least-confident quarterfinal was a lot more settled than 58 to 42 sounded. The rest of this page is the Monday-night read as it was written, with the prices re-pulled and the result folded in where a line would otherwise be stale.
The Quick Answer
Settled, Khachanov by retirement at 3-2 in the third on Wednesday, September 9. The prices on this page are the September 8, 6:02 a.m. ET pull the original edition was written on, Khachanov 58¢ to 59¢ and Blockx 41¢ to 42¢, plus a re-pull of every contract on September 16 for the settlement values, and the one line no other outlet has: the seller behind the 59¢ wall never got filled. They walked. My read was that the gap was an injury premium. Blockx said Monday night he was close to retiring with a rib injury, the overnight crowd bought Khachanov on that sentence, and the price still only moved two cents from its 11 p.m. level, because a 74,688-contract wall was sitting on the offer at 59¢. How the price got there, what a Blockx retirement did to a 42-cent contract, and what the title board said about the winner, who lost to Alexander Zverev on Friday, are all below.
How Khachanov And Blockx Got To Wednesday
Start with the one fact the two men share, because they have never played each other on tour. Blockx won the 2023 Australian Open boys' title, and the player he beat in that final was Learner Tien. On Monday night Khachanov needed five sets, three hours and 50 minutes and 323 points to get past the same Tien, 7-5, 4-6, 6-7(6), 6-1, 6-4, from two sets to one down. It is a transitive read across three and a half years and a junior draw, which is to say it is barely a read at all, but it is the only line between them, and it is part of why a 28 seed with a rib is not priced like an accident.
Khachanov's side of the bridge is the pedigree. The ATP Tour's own recap has him summing up Monday as "one extra ball coming back, one extra ball." It is his seventh major quarterfinal, his first since Wimbledon 2025 and his deepest run in New York since the 2022 semifinal, and his second round was the bigger scalp: he put out No. 3 seed Felix Auger-Aliassime 6-7, 6-3, 6-2, 6-2 on Thursday, the upset that emptied the top of this quarter of the draw. He is ranked No. 50 and unseeded.
Blockx's side is the rib, and two of the numbers in it argue against each other; the market has picked one. He beat No. 24 seed Francisco Cerundolo 6-3, 4-6, 7-5, 7-5 on Monday in three hours and 15 minutes, saved 14 of the 17 break points he faced, including a 0-40 hole at 5-5 in the third set, and hit 36 winners, and by the ATP Tour's own match report he was hurting from the second game on. "I was just holding on to be honest," he said afterward. "Even though I won that first set 6-3, it could have been the other way round." A doctor gave him medication during the match, "the doctor gave me some magical medication and that kept me going," and the quotes that moved the market came in the AFP write-up: "I was really close to retiring, to be honest," and "if I would have lost the third set, I think the chances were really high of me retiring." He added the line a trader hears loudest: "I had medication. So if you feel that much pain while having a lot of medication, that's not a good sign." The 14 of 17 is the case for the 42¢ contract; that sentence is the case against it, and 41 to 42 is where the market weighed them.
The win made him the first Belgian man to reach a US Open quarterfinal, a claim the ATP and AFP both make, and the youngest Belgian man in a major quarterfinal in the Open era; only three Belgian men had reached the last eight at any Slam before him, per the ATP. He started 2026 outside the top 100 and had to qualify for the Australian Open. He came into New York ranked No. 34, and his path here ran through No. 5 seed Flavio Cobolli in the third round before Cerundolo. Both men were on the same short turnaround, and until the tournament posted Wednesday's order of play the recovery clock was unknown to everyone.
What Kalshi's Price Says, And How It Got There
Kalshi listed the match as a pair of yes-or-no contracts, one per player, under event KXATPMATCH-26SEP09KHABLO; each paid $1 if its man won. Here is where the four men's quarterfinals stood at the same 6:02 a.m. ET snapshot on September 8, Tuesday's two matches included because they show what a confident quarterfinal price looked like next to this one, with the result each price was pointing at.
| Quarterfinal | Day | Kalshi price, Sept. 8, 6:02 a.m. ET (bid / ask) | Result |
|---|---|---|---|
| Carlos Alcaraz Vs Ben Shelton | Tuesday | Alcaraz 78¢ / 79¢; Shelton 21¢ / 22¢ | Shelton, 6-7(5), 6-1, 6-3, 1-6, 7-6(7) |
| Frances Tiafoe Vs Alex Michelsen | Tuesday | Tiafoe 57¢ / 58¢; Michelsen 42¢ / 43¢ | Tiafoe, 5-7, 3-6, 7-5, 6-3, 7-6(10-6) |
| Alexander Zverev Vs Botic Van De Zandschulp | Wednesday | Zverev 87¢ / 88¢; Van de Zandschulp 12¢ / 13¢ | Zverev, 6-2, 7-5, 6-1 |
| Karen Khachanov Vs Alexander Blockx | Wednesday | Khachanov 58¢ / 59¢; Blockx 41¢ / 42¢ | Khachanov, 6-2, 7-5, 3-2 ret. |
All four prices are the September 8, 6:02 a.m. ET snapshot the original edition was written on, and all four matches have been played; the results column is from the cited match reports, and the Tuesday rows went one each way: the 21-cent Shelton upset at 3:33 a.m., and the 57-cent favorite surviving, Tiafoe from two sets down against the 42-cent Michelsen.
What Moved Since September 13
Nothing moved after September 9; the market settled that evening, and the September 13 edit was a wording pass. What moved was everything between this page's 6:02 a.m. pull and the close, and the first thing that moved was the wall. It never got eaten. It got pulled. Khachanov printed 60¢ for the first time between 2 and 3 p.m. ET on September 8, on about 17,000 contracts traded since the snapshot, under a quarter of the 74,688 sitting on the offer, so the seller withdrew rather than getting filled. By 5 p.m. he was 60¢ bid, 61¢ ask, and apart from a one-hour dip to 59¢ bid around 7 p.m. he sat there through the night; at 6:02 a.m. on match day he was 60¢ to 61¢ and Blockx 39¢ to 40¢, with 159,000 contracts traded between the two legs. That was 1.4 percent of what the market would become: 11.15 million contracts by settlement, 4.34 million of Khachanov and 6.81 million of Blockx, about 96 percent of Khachanov's lifetime volume going through between 11 a.m. and the close on Wednesday. The crowd put 57 percent more contracts through the underdog's leg than the favorite's, 6.81 million against 4.34 million, and the gap widened once the match was on. Every price here was re-fetched from Kalshi's public market data on September 16.
| Contract | Sept. 8, 6:02 a.m. ET | Match day, 6:02 a.m. ET | Settled at | Lifetime contracts |
|---|---|---|---|---|
| Khachanov wins (KXATPMATCH-26SEP09KHABLO-KHA) | 58¢ / 59¢ | 60¢ / 61¢ | $1.00, 6:49 p.m. ET Sept. 9 | 4,341,360 |
| Blockx wins (-BLO) | 41¢ / 42¢ | 39¢ / 40¢ | $0.00 | 6,811,808 |
| Khachanov wins by over 1.5 sets | not on the page | not on the page | 92¢, fair market price | 56,326 |
| Khachanov -4.5 games | not on the page | not on the page | 93¢, fair market price | 49,702 |
| Over 35.5 total games | not on the page | not on the page | 15¢, fair market price | 162,627 |
The tape puts the retirement in the minute ending 6:45 p.m. ET, when 112,807 contracts took Khachanov from 96¢ to 99¢ and the price never moved again; Kalshi closed the book at 6:48:04. At one hour and 38 minutes that puts the first ball at about 5:06 p.m., and the minute ending 5:06 p.m. is the market pricing it: 203,380 contracts at 63¢ to 65¢, more than six times any minute in the eight hours before it. Then the thing I said to watch happened, and the market watched it too. Through the opening games, 5:09 to 5:23 p.m., the price bounced between 60¢ and 66¢ and Blockx traded as high as 42¢. From 5:25 to 5:27 p.m. Khachanov went 65¢ to 77¢ and Blockx 37¢ to 24¢, a three-minute move the size of a break of serve, and by 5:35 p.m. it was 84¢ to 16¢. The second set is what the 41-cent buyers were paying for: Khachanov sagged to a 72¢ print at 6:03 p.m. with Blockx back to 28¢ in the same minute, then 86¢, 91¢, 94¢ from 6:19 to 6:21 and a 352,879-contract minute at 92¢ to 98¢ ending 6:24 p.m., the largest of the match, which sits about where a 7-5 set ends on that clock. The break for 3-2 in the third lands on the tape as two minutes, 117,315 and 277,795 contracts at 96¢ to 98¢ ending 6:37 and 6:38 p.m., with the largest single print on the tape we have inside them, a 121,587-contract buy at 97¢ at 6:37:03. Seven minutes later he stopped.
The set and game contracts are the original page's rules paragraph, graded. The retirement clause lives in those siblings, not in the match market, and it says markets that "cannot be unconditionally settled will resolve to Fair Market Price": 25 games had been played when Blockx stopped, so over 35.5 games settled at 15¢, Khachanov by over 1.5 sets at 92¢ and Khachanov -4.5 games at 93¢, none of them at $1 or zero. Blockx by over 1.5 sets was the one sibling that could be settled on play completed, and it went to zero. The match contract needed none of that: a ball had been played, so it paid the full dollar, exactly as the page said it would. Back to the board, and to the row that was worth reading before any of this happened.
The row worth reading is the second one. Tiafoe against Michelsen was a cent closer to even than this match, so Khachanov-Blockx was not quite the closest price of the four; it was one of only two quarterfinals the market treated as competitive, and by Wednesday the Tiafoe match had been decided. Both spreads were one cent wide, which on Kalshi means buying both sides at the ask costs $1.01 for a contract pair that pays exactly $1. The market's take on the two matches was the same: someone is a modest favorite, and the sellers on each side are close enough together that nobody is guessing. The two competitive rows went to the favorite; the two lopsided rows split, and the 21-cent Shelton row is the one that reminds you what a 78-cent price is not.
It did not start that way. The Khachanov contract listed just before 10 p.m. ET on Monday night, and the first prints were an empty-book mess: a handful of lots at 80¢ in the first ten minutes, a 50¢ trade at 10:21 p.m., and a 54¢ fill by 10:43. Blockx's first real trade was 209 contracts at 46¢ at 10:24 p.m. By 11 p.m. the book had found 55 to 57 on Khachanov and 43 to 46 on Blockx. The 58¢ level was first bought in size just after midnight, a 1,507-contract lot at 12:25 a.m. among roughly 2,300 contracts that printed, meaning traded, at 58¢ before 1 a.m., and it did not hold; the price sagged back to 57¢ and sat there for four hours. The morning block did hold: between 5:18 and 5:49 a.m. another 2,350 contracts went through at 58¢, a 1,667-lot at 5:23 a.m. the biggest of them, and the first 59¢ prints of the market's life came at 5:40 a.m. The last fill before the snapshot was 59¢.
The direction of the trading is not subtle. Of the 16,446 Khachanov contracts that traded, 16,090 were bought by someone lifting the offer, paying whatever a seller was asking, and 356 were sold into a bid. On the Blockx contract, 6,454 traded, and the takers sold him more often than they bought him: 3,834 contracts sold against 2,620 bought. Add the two legs and roughly 19,900 contracts of aggressive money went Khachanov's way overnight against about 3,000 that went Blockx's. Picture a crowd reading the same medication quotes I read, and buying. That took the price from its 11 p.m. level of 55 to 57 up to 58 to 59. Which raises the question the rest of this page is about: why only two cents?
The Order Book: Where The Khachanov Buying Stops
Kalshi's order book, the list of resting orders waiting to be filled, answered it. On the Khachanov contract at the September 8 snapshot, the best bid at 58¢ had 3,808 contracts behind it. The best offer at 59¢ had 74,688. That was the wall, the single most lopsided number on this market. Every one of those 74,688 contracts was someone willing to sell Khachanov at 59¢, which is the same thing as someone willing to back Blockx at 41¢. Add the 6,020 contracts bid for Blockx directly at 41¢ on his own leg and there were more than 80,000 contracts of patient money waiting to take the Belgian at 41 cents, against about 10,000 waiting to take the Russian at 58.
Whoever was behind the wall, and market makers quote in this kind of size as a matter of course, the effect was the same: Khachanov could not print 60¢ until 74,688 contracts changed hands at 59, for as long as the order stayed there; a resting offer is a quote, not a promise, and it can be pulled the moment the order of play or a practice report changes the rib story. The overnight crowd bought 16,000 in eight hours. The crowd chased the favorite all night and ran into a seller that did not blink. Behind the wall it stayed thick: 5,266 contracts offered at 60¢, then 39,929 at 61¢ and 49,152 at 62¢. Compare the Blockx side, where the front of the book was thin, 6,328 at 42¢ before 23,955 at 43¢, and the shape of the market was clear. Buying Blockx a cent or two higher was easy. Buying Khachanov a cent higher was very hard. The book was boxed on the other side too: about 76,000 contracts were bid for Khachanov between 55¢ and 57¢, so the same market that would not let him print 60 would not let him sag to 54 either. That was a market that had decided the range and was arguing over two cents inside it, and the bigger pile of resting money sat on the Belgian's side of the ledger, whatever the takers did overnight. By 6:02 a.m. ET on match day the wall was gone and Khachanov was 60¢ bid, 61¢ ask; what happened to it is in the section above, and the answer is that nobody ate it.
Worked Example: 100 Contracts At 42¢
For a reader thinking about what 42¢ buys, the fee matters at this price more than anywhere on the board, because Kalshi's fee is largest on coin-flip contracts. One hundred contracts of Blockx at 42¢ cost $42 plus a $1.71 fee under Kalshi's 7 percent formula, so the trade breaks even if he wins about 43.7 percent of the time, not 42. Khachanov at 59¢ carries a $1.70 fee on 100 contracts and breaks even at roughly 60.7 percent. Our fee-schedule page walks the arithmetic; the short version is that the one-cent spread is not the only cent between you and fair value here, and on a match this close a cent and a half is a large share of the argument. Graded: the Blockx side lost the full $43.71, and the Khachanov side put up $60.70 with the fee and collected $100, a $39.30 profit that the 59-cent price and the retirement clause together bought. Tennis.com's match page showed the same 58-42 split before the match, though projections like that usually take their cue from the same market, so treat it as an echo rather than a second opinion. Neither number priced the rib on its own.
What The 42 Cents Is Really Paying For
Here is what the market was actually pricing, in the order I weighted it. First, the rib. Blockx said he was close to retiring, said the medication was not masking the pain, and then had a night's sleep and a day off before a Wednesday match against a man who is 6-foot-6 and hits through the court. Nobody who bought Khachanov at 57¢ in the middle of the night knew how that rib would feel on Wednesday morning. They were pricing a possibility, and 41 to 42 cents on a 28 seed who had just beaten a No. 5 seed and a No. 24 seed back to back is what the possibility cost. The contract's own fine print sharpens the point: Kalshi's rules say each market settles on the winner "after a ball has been played," and a withdrawal before the first ball is served resolves at a fair price instead, so the 42¢ was not a bet that Blockx shows up. It was a bet that he starts and finishes, because a retirement in the second set pays Khachanov's side the full dollar. That is the clause that settled this market: Blockx started, played 25 games, and stopped, and the Khachanov contract paid $1 exactly as it would have after five sets. Strip the injury out and the seed, the age, the ranking gap in Blockx's favor, and the form against Cobolli and Cerundolo would put him closer to even. The two-cent overnight move and the eight-and-a-half-point gap from even were the injury premium, and it is not hard to see why the market charged it.
Second, the mileage. Khachanov played 323 points and nearly four hours on Monday; Blockx played three and a quarter hours through the pain. A 30-year-old coming off a five-setter and a 21-year-old coming off a four-setter with a rib was a wash on paper, and the market treated it as one, but it is the reason both prices sat where they did rather than farther apart. Khachanov had done this before, a 2022 semifinal here and six previous major quarterfinals; the pedigree is what the 58 bought. Blockx saved 14 of 17 break points on Monday and dug out of 0-40 at 5-5 in the third with a bad rib. That is what the 42 bought. Neither man had a set of evidence against the other, because they had never played.
The counter to the market's read was the one I kept coming back to: Blockx's own numbers said the rib did not stop him from doing the hard things. Fourteen of 17 break points saved is not a stat line from a player who was holding on; it is one from a player who served his way out of trouble for three hours. If the treatment worked and the pain was manageable, the 41¢ side was paying an injury premium for an injury that did not show up on the scoreboard. The counter to that counter was his own sentence about the medication, and the market believed him. What I said to watch was the Wednesday order of play and the first two service games, because a rib shows up on the serve before it shows up anywhere else. The scoreboard never told us whether it did, because everything else gave out first: Blockx walked out with a brace on his right ankle and his thigh wrapped, lost a 6-2 first set, called for the trainer somewhere in the middle of it all, lost the second set 7-5, and retired after Khachanov broke him for 3-2 in the third, one hour and 38 minutes in. "I think my body just gave up," he said afterward, per ESPN, which listed leg, rib and back injuries; Khachanov said he "started to feel like he was suffering all over his body." The market that took eight hours to buy two cents did the rest in an afternoon.
What The Title Board Says About Wednesday's Winner
Kalshi's US Open men's champion board, event KXATP-26USO, put the winner of this match in context. At the September 8 snapshot Khachanov was quoted at 2¢ bid, 3¢ ask to win the tournament; Blockx was 1¢ bid, 2¢ ask, level with Alex Michelsen and a cent above Van de Zandschulp's 0¢ to 1¢. Every one of those contracts has since settled at zero, and the one row on that board that paid $1 is the one this paragraph was already pointing at. Divide each man's title price by his price to win Wednesday and you get his implied chance of lifting the trophy given he gets through: Khachanov's 2.5-cent midpoint over 58.5 is about 4 percent, and Blockx's 1.5 over 41.5 is about 3.6 percent. Whoever won on Wednesday, the board said he was somewhere between a 23-to-1 and a 28-to-1 shot from there, and the reason was one row up on the same board. Alexander Zverev was 27¢ to 28¢ to win the title and 87¢ to 88¢ to beat Van de Zandschulp, which made him the likely semifinal opponent for the winner of this match. In a four-quarterfinal draw that left Tuesday's two winners for the other semifinal, and Outlook India's quarterfinal report confirmed the Alcaraz-Shelton winner would meet Tiafoe or Michelsen there; Carlos Alcaraz was 55¢ to 56¢ to win it all from that half, and lost to Shelton at 3:33 the next morning. The market was pricing this quarterfinal as the match that decides who gets to lose to Zverev, and it priced that outcome the same for both men. That is how it went: Zverev beat Van de Zandschulp 6-2, 7-5, 6-1 on Wednesday night, beat Khachanov 6-3, 7-6(7), 7-6(6) on Friday, with Khachanov holding two set points at 6-4 in the third-set tiebreak per Tennis Majors, and beat Shelton 6-3, 7-6(2), 5-7, 6-2 on Sunday for the title. His 27-to-28-cent contract settled at $1 at 6:00 p.m. ET on September 13. Khachanov's title contract, 3¢ to 4¢ on the morning of the quarterfinal, settled at zero at 6:26 p.m. ET Friday, and he left New York as the lowest-ranked US Open men's semifinalist since the rankings began in 1973, per ESPN.
That is the frame that made the 58-to-42 split easier to read. The market did not believe Wednesday's winner was going far, and it was right by two tiebreaks. It was arguing about a single match between two men who had never played, one of whom may or may not have been whole, and a single match with a hurt player in it is the hardest thing on the board to price. The crowd took one side of that argument overnight in size. A wall of resting money took the other and did not move until match day. An 80-cent opening print into an empty book, a sell-off to 54, two cents of buying since 11 p.m., and 74,688 contracts saying not a penny more: that is what a market looks like when it knows exactly how much it does not know. It knew the price of a hurt player to within two cents, and the body settled the argument for it.
The books have long since taken the Khachanov-Blockx line down, and the live odds screen is where to shop the next tennis moneyline across every major book against what Kalshi is showing. If pricing one quarterfinal is not your game, OddsShopper's free expert picks cover the tournament the conventional way. For the wider picture, the US Open odds comparison across Kalshi, Polymarket and the sportsbooks maps the whole board, the men's champion board page prices the whole bracket, the Cincinnati final page keeps the receipt on the last Grand Slam-level match we priced this way, our Kalshi sports guide covers how the match contracts settle, and the daily Kalshi picks hub grades the panel's calls in public.
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Prices quoted are the snapshots named above; every contract on this page has settled, and the settlement values are from Kalshi's public market data as re-pulled on September 16, 2026.
Hero illustration: OddsShopper, in the house collage style. ; photos cropped, toned, and composited.
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