Khachanov Reaches 2026 US Open Semifinals After Blockx Retires in Third Set

The scoreboard read 6-2, 7-5, 3-2. Karen Khachanov was preparing to serve the sixth game of the third set when Alexander Blockx raised his hand. It was not a request for a towel, not a request for a new ball. It was the signal to stop — the kind of signal no official wants to see and no ticket holder pays to witness.

Blockx walked to his chair and sat down. The strapping around his left thigh had been visible for a while. The tournament medical team worked on both his lower leg and his back. Minutes later, the young Belgian stood up, shook hands with his opponent and the chair umpire, and left the court. The US Open quarterfinal ended mid-stream, leaving Khachanov a semifinal place and leaving the audience a far bigger question than the scoreline itself.

The naked eye sees a player retire. The referee's eye sees a chain of decisions that began long before that hand went up.

What happened before the hand went up

Blockx arrived in the quarterfinals as the No. 28 seed — no small position for a young player, but not enough for anyone to call him favourite against an opponent who had beaten big names on hard courts. Khachanov went against every projection: unseeded, arriving in New York at a stage when most of his generation had already faded.

This is the third Grand Slam semifinal of Khachanov's career, and his first since the 2026 Australian Open. The last time before that he reached the last four of a major was at the 2026 US Open itself. Three years, three ceilings, two surface types, one trajectory that was never straight.

The US Open is the final Grand Slam of the year, played on acrylic hard courts, spanning two weeks and usually closing in the second week of September. For players who go deep, it is the fourth consecutive block of a calendar that began in January — a detail anyone reading the tournament allocation table has to pause over.

In the other half, the picture is clear. Khachanov will face the winner between Alexander Zverev, the top seed, and Botic Van De Zandschulp, in a semifinal scheduled for Friday. The other semifinal is an all-American meeting between Ben Shelton, the No. 8 seed, and Frances Tiafoe, the No. 11 seed. For the host media, that is the match worth talking about. For anyone tracking rules and workload, the match that just finished on the main court is the data worth reading.

Re-reading twenty games through a referee's eye

Based on my experience covering matches on North American hard courts, a quarterfinal that ends in the fifth game of the third set is usually misread in one of two directions. The first calls it luck. The second calls it tragedy. Both ignore most of the data.

The first two sets followed the script Khachanov had built all tournament: a high first-serve points won rate, returns driven deep into the opponent's left leg, and return games stretched so long that the opponent paid a physical tax every time he stepped to the baseline. The first set closed 6-2. There is nothing miraculous in that number; it is the consequence of one player holding his footwork while the other slowly lost his.

The second set is the interesting part, closing 7-5. Blockx recovered the shape of the match, extended each game, and at one point forced Khachanov to serve from behind. The difference sat in the final games: when Khachanov had to hold, he chose the safe option — heavy topspin down the middle, minimising line risk. When Blockx had to hold, he still went for the lines. That is the kind of difference that only appears when you rewatch point by point, not when you read a scoreboard.

There is a rule detail almost nobody notices here. Under ATP regulations, cramping does not earn a medical timeout. A player may only be treated at changeovers. Injury does: each medical timeout runs up to three minutes, limited to two per match, not counting changeovers and set breaks. The boundary between the two concepts is not decided by a machine but assessed on the spot by the medical team and the umpire. When Blockx was treated on both his lower leg and his back, the question stopped being "where does it hurt" and became "which threshold has his body crossed".

The third set lasted only five games. At 3-2, Blockx stopped. In rules terms, this is a retirement. The score stands, Khachanov is credited with the win, and prize money and ranking points for both players are allocated according to the round reached. A withdrawal before the match begins is recorded as a walkover; a withdrawal mid-match leaves everything that happened on court intact. No panel sat down to review footage. There was no replay room. A body delivered the final ruling, and the rulebook simply recorded it.

I do not trust the final ruling; I trust the chain of reasoning that leads to it. And the chain here runs back toward the calendar, not toward the player.

The stands and the schedule

The easiest and most wrong way to tell this story is to call Khachanov's semifinal place a gift. He played two and a half sets, more than twenty games, at quarterfinal level of a Grand Slam. Under the rules, that is a completed win, not a wildcard. Nobody calls a player who wins two straight sets fortunate merely because a third set did not go the distance.

The louder point sits in the stands. They bought tickets for an evening on the main court and lost a set and a half plus the entire late-match drama. The reflex is to blame the player. But this match was scheduled in a late slot, after a season stretching nearly eleven months, on a hard court that grinds knees, calves and backs. Injury here is not a random accident. It is the output of a system designed to maximise broadcast hours.

Technology does not save anyone in this scenario either. Electronic line calling can place a ball outside the line to the millimetre. It cannot measure the fatigue in a calf, and certainly not the fatigue in a decision to keep playing. VAR did not kill football; it exposed a truth we preferred to deny — and in tennis, the limit of technology sits exactly where the limit of the human begins.

The gap the rulebook leaves open

Rules do not exist to punish; they exist so a match does not become a lottery. But the current rulebook leaves a large gap exactly where Blockx sat down: no clear disclosure process for injury status, no mechanism to help spectators understand why a player is treated and then still walks out to serve, and no limit on the match load a body must carry in a season.

Khachanov will walk into the semifinal against Zverev or Van De Zandschulp, with fewer rest days if that pairing goes long. Shelton and Tiafoe will fight for the remaining place, and the host nation will point its cameras there. As for this quarterfinal, in the tournament record it will occupy a single line: retired.

The best official is the one who knows where he is wrong before anyone points it out. Tonight, no official was wrong. Only a body was right — and right in a way nobody wanted.