Khachanov Reaches a Third US Open Semifinal: What Lay Behind Blockx's Mid-Match Stop

The fifth game of the third set. The score read 3-2 for Karen Khachanov. Alexander Blockx walked to the service line, tossed the ball, put it in play, and then stopped. I have sat in tennis stadiums long enough to tell a few kinds of stopping apart. There is the stop to watch a passing shot graze the line. There is the stop because the umpire has just called a foot fault. Then there is the third kind, the kind Blockx showed that afternoon: the stop of someone who has just heard something inside his body that he does not want to believe.

I had seen the strapping earlier. Early in the second set, Blockx called the trainer out. They wrapped the upper left thigh, then worked on the lower leg. Midway through the third, they worked on his back. Three regions of the body for one Grand Slam quarterfinal. Nobody straps three regions as a joke.

Khachanov won the first set 6-2 and the second 7-5. In the third he led 3-2 when Blockx stopped. The match ended there. A semifinal place, the third Grand Slam semifinal of Khachanov's career and his first since 2026.

People will remember the score. I will remember the way Blockx placed his hand on his left hip in the second game of the third set, and the way he no longer chased balls he had been chasing. The forty-page notebook never lies.

A semifinal settled by silence

The men's quarterfinal began in an entirely ordinary way. The stands were not yet full, the organizers were still adjusting microphones, and the two players warmed up like any other quarterfinal pairing. Karen Khachanov walked on with the bearing of a man who had nothing left to lose. Alexander Blockx walked on with the bearing of a young player who wanted to prove something.

Khachanov is a Russian player born in 2026, part of the generation that emerged in the late 2010s and then traveled a road that was anything but straight. He reached the US Open semifinals in 2026 and the Australian Open semifinals in 2026. Both times he was stopped by opponents rated more highly than him. At twenty-nine, people tend to say a player is past his peak. But tennis does not read age the way collision sports read it. Tennis reads age through the number of steps per point, through the depth of the serve in the twelfth game, through whether a player still dares to step inside the baseline on break point.

Blockx is a Belgian player, nearly a decade younger than Khachanov, seeded twenty-eighth here. A young player seeded at a Grand Slam means the system recognized him before the public learned his name. I keep the habit of tracking low seeds, because that is where stories are consumed fastest and discarded fastest. A young player is celebrated when he wins a round, then forgotten the moment he picks up an injury. The resource structure behind those fairy tales almost never changes.

What decided this semifinal place was the body. Blockx stopped playing while trailing 2-6, 5-7, 2-3. Three regions were treated within a single match: the upper left thigh, the lower leg, and the back. A player does not naturally develop three problem areas in one afternoon. Usually it is a sign of something accumulated, or of a root injury in the back that forces the body to compensate, after which other regions absorb the consequences one by one.

Khachanov will meet the winner of the match between top seed Alexander Zverev and Botic Van De Zandschulp, in a semifinal scheduled for Friday. The other half is an all-American meeting between eighth seed Ben Shelton and eleventh seed Frances Tiafoe.

Looking at those four names together, one immediately sees an uneven distribution of attention. Shelton against Tiafoe features two Americans, the loudest applause in the stadium, and a local story that sells easily to a television audience. Khachanov's half features an unseeded player, a little-known Belgian, and a Dutchman. The way a tournament gets retold never fully reflects its quality.

Set one: when the serve becomes defense

The first set finished 6-2. The scoreline sounds easy, but how it unfolded is where I want to pause.

Khachanov served first. Across his opening two service games, he did not try to win each point quickly with the serve. He hit his spots, accepted rallies, and looked for the opening on the third or fourth ball. That is the mindset of a man who treats the serve as defense rather than a finishing weapon. The serve holds the rhythm, holds the initiative, and forces the opponent to pay with his legs. People watch the winner; I watch the gap that opens before the winner is struck.

Blockx returned with his legs. He stepped inside the court, took the ball early, trying to steal time from Khachanov. But taking the ball early demands healthy legs and a torso that can rotate fully. While the left thigh had not yet declared itself, that return pattern was still dangerous. By the end of the first set, I noted one small detail: twice Blockx finished his return and then stood looking toward the corner of the court he had just left open. A normal player does not stand and stare at the space he has vacated. It is the sign of someone beginning to recalculate whether the body can keep up with the head.

The difference in the first set lay in Khachanov's return games. He did not win with spectacular returns. He won by putting the ball back, deep enough and heavy enough, into the area that forced Blockx to move laterally. In one mid-set game I noticed, Khachanov returned three consecutive balls into the same zone, making Blockx run the same direction three times. On the fourth, he changed direction. Blockx had no legs left to compensate. That is not luck. That is an experiment.

Khachanov took it 6-2 with a steady first-serve percentage and a low double-fault count. For a tall player, the serve is always a crutch, but a crutch only has value when a structure stands behind it rather than a lone player. The first set showed that behind Khachanov's serve there was a structure.

One more thing stood out: Khachanov rarely hit a purely defensive second serve. He still hit deep, accepting moderate risk, to hold the initiative in second-serve situations. The second serve is where players reveal their nature. The fearful slice it; the confident still attack. That afternoon, Khachanov belonged to the second group.

Set two: 7-5 and the history of an injury

The second set was the most important of the match, even though it ended 7-5 and took up only two pages of my notebook.

By the second set, the upper left thigh had been strapped. That means the medical team had identified the problem and the player had decided to continue. In tennis, an injury to the left thigh affects more than running. It affects the serving stance, the drive from the front leg, the ability of the hip to rotate. Once a leg hurts, the body automatically seeks compensation. The back muscles carry the load. The calf adjusts. One problem becomes three, logically and cruelly.

The second set saw an explosion in the quality of Blockx's returning. He won some memorable points, including returns placed into Khachanov's feet that stopped him from stepping in. That is how a young player handles a body beginning to betray him: try to end points earlier, try to hit shorter, try to cut the number of steps per point to a minimum.

But the strategy of reducing steps carries a price. It drives up the unforced error rate. It turns every point into a gamble. In the second set, my notebook recorded stretches where Blockx won points in a row and then lost points in a row. No rhythm held for long. That is the sign of someone playing on will more than on body.

In the eleventh game of the second set, Khachanov had the most important point of the match. He stayed calm, sent the ball into the area that forced Blockx to run to the wrong side, and won the game. The twelfth game closed the set at 7-5. People will call that the turning point. I call it the consequence of a body that had lost its advantage earlier, only without showing it yet on the scoreboard.

What happened in the second set also revealed an often-unmentioned side of elite tennis: the gap between two players does not lie in pure technique. It lies in who can still maintain that technique when the body stops cooperating. Khachanov could. Blockx could not sustain it to the end.

Set three: three regions and one decision

The third set changed the tempo entirely. Long rallies decreased. Balls Blockx had chased to the end in the first set were now met with a half-run and a stop. Not because he changed tactics. His body had made the decision for him.

Midway through the third set, the trainer returned and worked on his back. In tennis, a back injury is the hardest kind to hide. It affects the serve, the forehand, the rotation of the entire upper body. Viewers at home do not see it. They only see a player hitting more balls out. I saw a man trying to hold his posture while his upper body refused to obey.

Khachanov led 3-2 when Blockx stopped. The match ended there.

What I want to record about this decision is how rational it was in the context of a future being staked. A young player seeded twenty-eighth, at an age where every Grand Slam is an opportunity to accumulate, has to weigh playing a few meaningless more games against protecting the rest of a career. Stopping at 2-6, 5-7, 2-3 is the decision of someone who respects his body more than the applause.

There is a rhythm in matches where a player retires: crowds go quiet in a different way than when a match ends normally. They go quiet because they were not prepared. They came to watch a match and received a medical decision. Khachanov shook hands, waved to the crowd, and left the court with the face of a man who knew this win would be remembered with an asterisk.

That is the fate of many quarterfinals. The winner does not get to choose how he wins.

What the notebook reveals

I have followed Khachanov long enough to know that his value does not lie in numbers that make people gasp. He is a player of long games, of big points held with a first serve, of returns that put opponents on the run. In my notebook, he belongs to the group of players whose win rate never stands out as much as their consistency.

Three Grand Slam semifinals in a career is a milestone. It is not the milestone of a Grand Slam champion. It is the milestone of a player who is always present in the deepest part of tournaments, in the region you only reach by avoiding mistakes in the early rounds. Consistency in that region is underrated, because it does not produce highlights.

In this match, what I recorded most was not Khachanov's shots but his intervals. The interval between the end of a point and the next serve. Good players control that interval. They stretch it when they need to breathe, shorten it when they need to sustain pressure. Khachanov managed that rhythm better across all three sets. It is a skill counted in no statistic on television.

One more thing needs saying: a win by retirement is often dismissed. That is unfair to both players. Khachanov won the first two sets before his opponent stopped, and those two sets were played at a quality that showed the situation was not random. Blockx played well at certain moments, and that should not be erased along with his injury.

The reverse angle: the "unseeded" label

The way this story will be told on broadcast is easy to predict. An unseeded player reaches the semifinals after his opponent retires. An injury to the thigh, calf, and back. A semifinal against the top seed. The story has enough to fill thirty seconds, and precisely because of that it will be told superficially.

The "unseeded" label at a Grand Slam misleads more than it informs. Seeding is determined by ranking at a given moment. A player who has reached the semifinals of two different Grand Slams does not become a mid-level player simply because he is unseeded at this one. The label describes position, not quality.

Conversely, an injury to Blockx should not be read as a complete explanation of defeat. Read that way, it erases the work Khachanov did in the first two sets. That work was building points by forcing the opponent to run into the areas he wanted. Any player has to choose between ending points early and controlling the match. Khachanov chose control.

There is another angle rarely mentioned: the distribution of attention. That night, the all-American semifinal between Shelton and Tiafoe would take most of the broadcast time and most of the headlines. The Zverev-Van De Zandschulp match would be mentioned as a top-seed contest. Khachanov's half was placed at the end of the bulletin. This pattern repeats at every tournament, in every sport. Fairy-tale stories in underrated sections are consumed quickly and discarded, while the structure of resource and attention allocation behind them almost never changes.

The practice court has no spectators, but every answer lies there. Players who sustain form across seasons are those who resolved the questions of body and rhythm long before the tournament began.

The semifinal ahead

Khachanov will meet the winner of Zverev and Van De Zandschulp on Friday. That is a test at a different level. The top seed means a player with a heavy serve, deep returns, and the ability to hold structure across sets. Van De Zandschulp is a different variable, a player who can hit flat and create awkward rhythm.

What Khachanov needs to keep is not the thrill of momentum. It is the serving structure he built in the first set, and the ability to return into areas that force opponents to run. By the semifinals, no opponent leaves open space. If he holds the rhythm he showed, the semifinal will not be a match he enters as the underdog.

When everyone watches the ball, I only see the guiding hand from the sideline. For Khachanov, that hand lies in how he structures each service game. What I will watch on Friday is not the winner, but the gap he opens before the winner is struck. Because that is where the match is truly decided.