Khachanov Reaches Third US Open Semifinal: The Data Behind an Unseeded Run

On the 97th minute of the quarterfinal, with Karen Khachanov leading 6-2, 7-5, 3-2, Alexander Blockx put his racket down. The 28th seed's left thigh had been wrapped since the second set. The medical team had come on court twice, treating both his lower leg and his lower back. The umpire declared the match over. The crowd applauded — but not for a winning serve, not for a perfect net charge. It applauded a stoppage.

At that very moment, as every camera turned toward a doubled-over Blockx, I reopened my serve-tracking sheet for the three completed sets. A semifinal is not decided in the second someone lets go of a racket. It is built in the games no broadcaster replays. When the world watches the withdrawal, I watch the seventh game of the second set.

This is Khachanov's third Grand Slam semifinal, and his first since 2026. Before that came the 2026 US Open semifinal and the 2026 Australian Open semifinal. Three times, three different tournaments, one repeating pattern: this Russian player is not the champion, but he is always present in the round others must leave.

The quarterfinal was played on hard court — the surface where my longitudinal tracking shows Khachanov is most effective. He is not the hardest server in the draw, but he is the type who turns the serve into a tactical tool. Hard courts do not forgive hesitation. Every dropped service game is a debt, and Khachanov entered this match with an impressive repayment record.

Blockx, the 28th seed, was the higher-ranked player on paper. But rankings measure the past, not the present. Across the first two sets, Khachanov won 6-2 and 7-5. The opening set was almost one-way traffic. The second was tighter, and that is the most telling part, because it unfolded during the stretch when Blockx began to show signs of trouble.

My read of those first two sets shows what the scoreline leaves out. Khachanov did not win because Blockx weakened. He won because he had seized control of the tempo before his opponent's injury became the deciding factor. In the first set he grabbed the initiative from Blockx's earliest service games. In the second, when Blockx fought back to 5-5, Khachanov kept a cool head across the final two games to close the set at 7-5.

That is the noteworthy detail. An unseeded player, facing a seed, held his composure exactly when his opponent was rallying. Had Blockx been healthy, the second set might have gone another way. But 5-5 is the moment where the mind usually collapses. It did not.

I have written before that a small discovery at a small tournament can roar at a major years later. The same holds for Khachanov: the signs of deep Grand Slam runs appeared at the 2026 US Open, repeated in Melbourne in early 2026, and now resurface in New York. When a pattern repeats three times across three different contexts, it is no longer luck. It is structure.

And that structure shows in how Khachanov handles the serve in decisive games. He does not serve for a direct ace every time. He serves to put Blockx in a position to return from disadvantage, and from there opens the next shot. That is the serve of a chess player, not a thrower. On hard court, where the time budget of each point is compressed, this kind of serving accumulates into pressure the scoreboard cannot measure.

This is where I have to be careful, because data can be misread in favor of a story already decided. The biggest temptation is to call Khachanov "lucky." A semifinal arriving from an opponent's retirement sounds unglamorous, and the media likes that label. But the "lucky" label ignores the most important thing: a player is only in a position to benefit from a stoppage if he already led by two sets. Luck does not lead 6-2, 7-5. Structure leads 6-2, 7-5.

Yet I do not read too far either. A win by retirement is not proof of a title. It is a signal, not a verdict. The correlation between an opponent retiring and Khachanov reaching the semifinal says nothing about his ability to beat Zverev or Van De Zandschulp next. Blockx's injury is a variable, and a variable is not a cause. This is the point most commentary will skip when it rushes to crown Khachanov a contender.

Moreover, the retirement win itself can be a trap. A player entering a semifinal without completing a full quarterfinal can lose rhythm. Three sets and two and a half sets are two different workloads. Khachanov arrives on Friday with less than one set of match play compared with what a normal quarterfinal demands. For a 29-year-old, that extra rest could be an advantage, or it could be a gap in rhythm. My data on retirement wins shows both scenarios have occurred.

Khachanov's next opponent will be the winner between top seed Alexander Zverev and Botic Van De Zandschulp on Friday. In the other half, eighth seed Ben Shelton meets eleventh seed Frances Tiafoe in an all-American semifinal. That sets up a familiar position for Khachanov: the unseeded man standing among the seeds.

I will track Khachanov's semifinal the same way I track every one of his matches: not by the final score, but by how he builds each game. Because if he wins, some will call it opportunity. If he loses, some will call it a ceiling. Both are lazy readings. On Friday, the data will tell us who Khachanov really is. Data never lies — but it took me years to know when it tells half the truth.