Polymarket's "Will Carlos Alcaraz win the 2026 Men's US Open?" contract, which this blog priced at 56.5c two days ago heading into his quarterfinal against Ben Shelton, closed at 0 overnight after Shelton won the match in five sets, the latest finish in US Open history. Shelton's own title contract - flat around 7c through the evening before the match - now prices 35.9c as of 2026-09-09 11:35 UTC, making him the field's second choice behind Alexander Zverev at 44.8c. The event has traded $1.03M over the past 24 hours on $743K of liquidity. Numbers below are from Gamma and the CLOB, fetched at that time.
01The matchFive sets, one tiebreak, and a 3:33am finish
Defending champion Carlos Alcaraz and two-time major semifinalist Ben Shelton played the quarterfinal on Arthur Ashe Stadium starting Tuesday night, September 8, and it didn't end until 03:33 local time Wednesday morning - the latest a match has ever finished in the tournament's history. Shelton won it 6-7(5), 6-1, 6-3, 1-6, 7-6(10-7): Alcaraz took a tight first-set tiebreak, Shelton responded by winning 11 of the next 13 games to take sets two and three, Alcaraz leveled with a 6-1 fourth set, and Shelton closed it out in the US Open's 10-point deciding-set tiebreak. It was Shelton's first win over a top-three player and his first over Alcaraz in five meetings.
Gamma flipped Alcaraz's contract to closed: true with
outcome prices frozen at ["0", "1"] within minutes of match
point. Novak Djokovic's contract has been closed at 0 since August 31,
when he lost in the first round to Mariano Navone - his first
opening-round Grand Slam exit in two decades. Between Djokovic, Alcaraz,
and Jannik Sinner's pre-tournament withdrawal covered on this blog August
30, three of the field's biggest names are out before the semifinals.
A mirror image, set by set
The two contracts trace the match almost exactly. Alcaraz peaked at 61c after taking the opening tiebreak, then fell in three stages as Shelton won 11 of 13 games across sets two and three - bottoming at 23c - before Alcaraz's 6-1 fourth set pulled him back to 45.5c. The deciding tiebreak went the same way the whole match had: both contracts moved with every point until Shelton closed it 10-7, at which point Alcaraz's price dropped from 40c to 0.05c in about fifteen minutes and Shelton's jumped from 16c to 35.4c over the same stretch.
03What's leftAn all-American semifinal, and a new favorite
2026 US OPEN WINNER YES 24H
Zverev 44.8c +17.7c
Shelton 35.9c +28.2c
Tiafoe 9.4c +5.1c
Khachanov 4.0c +1.3c
Alcaraz 0.0c -56.5c
Shelton's win, combined with Frances Tiafoe's five-set comeback over fellow American Alex Michelsen the same day (5-7, 3-6, 7-5, 6-3, 7-6(6), from two sets and a break down), sets up an all-American men's semifinal - Shelton versus Tiafoe. It's only the second all-American men's Grand Slam semifinal since 2005: the first was the 2024 US Open, when Taylor Fritz beat Tiafoe in the same round en route to the final. Tiafoe's contract is up 5.1 points on the day to 9.4c, giving the pair a combined 45.3c of the field between them. The other semifinal spot is still open: Alexander Zverev, the tournament's No. 1 seed, plays Botic van de Zandschulp in a quarterfinal later Wednesday and is already priced as the new outright favorite at 44.8c, up 17.7 points on the day, ahead of a ball being struck. Shelton's order book shows the repricing has settled rather than continuing to move - a 0.1c spread, with roughly 950 shares bid at 35.8c against about 1,670 offered at 35.9c.
04Following it liveWatching a ladder reshuffle in real time
A dozens-of-outcomes title market like this one reprices in bursts - long stretches of near-silence between matches, then a single game or tiebreak moving every contract on the board at once, the way Alcaraz's did tonight. polymarket-tui puts every outcome in an event on one screen with its own price and 24h change, so a moment like this shows up as a ladder that visibly flipped order rather than one number you have to already know to go looking for.
$ uv tool install polymarket-tui
$ polymarket-tui
No account is needed to browse markets, books, and charts. The install page has Homebrew and one-liner options.