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Sports · US Open 2026 · Men's Singles · Quarter-finals
Alexander Blockx vs Karen Khachanov — 6-2 7-5 3-2 ret.
| Karen Khachanov✓ | 6 | 7 | 3 |
 Alexander Blockx | 2 | 5 | 2 |
def. by retirement
Final · Wednesday, September 9, 2026 · Quarter-finals
Result
Blockx retired at 2-3 in the third, and he had been in trouble from the opening set: a doctor was called in the break after it — for a blister on his right foot, Belgian reports say — and a physiotherapist worked on his lower back in the break after the second. Khachanov broke twice in that first set, both times on a forehand error, then saved the only two break points he faced all afternoon while serving it out. The second went with serve to 5-5 before he took the single break point of it, on a Blockx double fault and two more forehands missed. He broke again for 3-2 in the third with a backhand winner off a 120 mph serve, and Blockx retired without playing another point, embracing him at the net. It is Khachanov's third Grand Slam semi-final and his second here, four years after he lost the 2022 semi-final to Casper Ruud. Blockx, 21, was the first Belgian man to reach a US Open quarter-final and the youngest Belgian into a major's last eight in the Open Era. "I saw that he was suffering all over his body," Khachanov said.
Alexander BlockxRows the source hadn’t published are left off rather than guessed.
At this Stage
The quarter-finals are the last eight, played across Tuesday and Wednesday. Everyone still here has won four matches on these courts, which is enough that seedings have stopped explaining anything and the form of the fortnight explains most of it. Four of the eight are gone within two days; the other four play for a place in the final.
Alexander BlockxRound of 16
Quarter-finals
What we know now
Court: Arthur Ashe Stadium
Match length: 1:38
Watch: ESPN · ESPN2 · ABC · ESPN app
What I said beforehand
The preview, frozen before the first serve. Clearly dated, never rewritten — that's the deal that makes the pick worth anything.
The tidy version of this is form against experience, and the numbers are unusually obliging about it. Blockx is 24-15 for the season with a Masters 1000 semi-final and an ATP final in it, has gone from No. 116 a year ago to No. 26 in the live rankings, and has beaten the fifth seed and the twenty-fourth in the last four days. Khachanov is 30, ranked 50th — his lowest since June 2017 — was 16-18 for the season when he landed in New York, and had lost every North American hard-court match he played beforehand. He is also playing his seventh Grand Slam quarter-final against a man playing his first, has two major semi-finals and an Olympic silver medal, and beat the third seed here in the second round. What the ranking gap hides is that on hard courts they are nearly level: Tennis Abstract has Blockx 1770 to Khachanov 1742, about 55-45, because Blockx's best tennis this year has been on clay and his career hard-court record is 22-23 against Khachanov's 220-169. The court-time argument that usually decides a quarter-final does not work here either — 10h33 to 10h52 over four rounds, and a full rest day for both. So it comes down to two bodies. Khachanov has three hours and fifty minutes of five-set tennis in his legs from Monday night and finished at 9.37 p.m.; Blockx has a rib he said would probably have made him retire had he lost the third set, and four hours more recovery. I take Blockx, barely, and this is the closest call of the round.
The case for Alexander Blockx
53% to winBlockx has beaten a top-ten player, a top-25 player and a former Masters champion inside a fortnight, and he did the last of those on one lung: sharp rib pain from the second game, treatment at 3-2 in the first set, and by his own account a retirement he was close to taking. He won anyway, by four points across 43 games, saving fourteen of the seventeen break points he faced. He is the first Belgian man ever to reach a US Open quarter-final and the youngest Belgian into a major's last eight in the Open Era, and none of it is a fluke run: he made the Madrid semi-finals in April as a late call-up, beating Auger-Aliassime, Cerundolo and the defending champion Ruud on the way, and reached a first ATP final at Estoril in July. He is four hours fresher than Khachanov out of Monday, six inches of serve taller than the ranking gap suggests, and 21 years old with, on his own reading, a lot still missing from his game.
The case for Karen Khachanov
47% to winKhachanov has been in this position six times before and Blockx has never been in it once. He has reached the semi-finals of two majors — here in 2022 and at the Australian Open in 2023 — has an Olympic silver medal, seven ATP titles including the 2018 Paris Masters, a Davis Cup, and 329 tour-level wins to Blockx's 22. He beat Felix Auger-Aliassime, the third seed, in four sets in the second round, and he has just won a match he was two sets to one down in, which is the specific thing a best-of-five quarter-final debutant has never had to do. The five-setter cuts both ways: it cost him three hours and fifty minutes, and it also settled the question of whether the legs are there. His own account of the fortnight is that he arrived emotionally low and found a flow — the phrase he used was a moment of appreciation — and a man playing that freely at 30 with nothing to defend is a harder out than his ranking says.
Both cases written 2026-09-08, before the first ball — frozen into the record exactly as written, whatever the result. The percentages are mine — opinions with a percent sign on. They add to 100 because tennis has no draw to hide the rounding in.
My locked pick: Alexander Blockx to advance ✗ WRONG
“Hard-court Elo has it 1770 to 1742, about 55-45 to Blockx, and the usual quarter-final tiebreakers cancel: court time is level at 10h33 to 10h52 and both have a full rest day. Shaded back toward Khachanov for a seventh major quarter-final against a first, and for Blockx's rib; shaded forward again because Khachanov carries three hours fifty of five-set tennis from Monday night. The closest call of the round.”
Locked 2026-09-08 01:10 UTC — rendered verbatim from the pick ledger; never a fresher, hedged version
Tale of the tape
Alexander BlockxKaren KhachanovPlayer vitals: US Open official player feed (usopen.org) and Tennis Abstract career match logs · as of 2026-09-04.
Career head-to-head: ATP Tour official head-to-head record and Tennis Abstract tour-level match logs · as of 2026-09-07.
Storylines
- They have never played each other — the ATP's head-to-head page reads 0-0. It is a first meeting at the eighth major quarter-final for one of them and the first for the other.
- Blockx is the first Belgian man to reach the US Open quarter-finals, the youngest Belgian to reach a major quarter-final in the Open Era, and only the fourth Belgian man to reach a Grand Slam last eight. He had won one Grand Slam main-draw match in his life before this fortnight, and this is his US Open debut.
- Khachanov competes as a neutral athlete and is shown without a flag, as are Medvedev and Rublev. He is playing his seventh major quarter-final and has never won a major; his two semi-finals are the 2022 US Open and the 2023 Australian Open.
- Both men beat Felix Auger-Aliassime in 2026 — Blockx in the Madrid third round in April, for his first top-ten win, and Khachanov here in the second round, in four sets.
- Blockx is the fifth man born in 2005 or later to reach a major quarter-final, joining Learner Tien — whom Khachanov beat to get here — Joao Fonseca, Rafael Jodar and Jakub Mensik.
- Khachanov reached this by winning from two sets to one down against Tien in three hours and fifty minutes, finishing at 9.37 p.m. on Monday. Blockx had finished four hours and twelve minutes earlier the same day.
- The winner meets Frances Tiafoe, Alex Michelsen, Ben Shelton or Carlos Alcaraz in the semi-final. Tiafoe plays Michelsen on Tuesday, which guarantees an American in the last four.
Head to head
They have never met. The ATP's official head-to-head page reads 0-0, and Tennis Abstract's tour-level logs record no meeting on any surface. Blockx has, however, played the man Khachanov beat to get here: Learner Tien beat him in the 2025 Next Gen ATP Finals title match in Jeddah, a rematch of the 2023 Australian Open boys' final, which Blockx won 6-1 2-6 7-6(9).
Source: ATP Tour official head-to-head record and Tennis Abstract tour-level match logs · as of 2026-09-07.
Court & schedule: Arthur Ashe Stadium, Wednesday 9 September. The US Open posts each day's order of play the evening before; this one is on the board. (Official US Open order of play, as of 2026-09-08)
Weather: Sunday — the men's final, and the last match of the fortnight — is 78°F with showers and thunderstorms 95% likely, the wettest day of the two weeks and the one day that cannot be pushed back. Ashe closes its roof and plays on. It clears overnight: 20% Sunday night, 20% Monday, then dry and sunny from Tuesday. (National Weather Service New York forecast, as of 2026-09-13)
Venue: USTA Billie Jean King National Tennis Center, Flushing Meadows, New York — hard.