US Open ATP Quarter-Finals Round-Up | Karen Khachanov reaches semis and seals Top 30 return after Blockx retires

Karen Khachanov has reached the US Open semifinals after Alexander Blockx was forced to retire during their quarter-final, with the Russian leading 6-2, 7-5, 3-2 at the time. The result brings an early end to Blockx's breakthrough run in New York, while Khachanov moves into the last four at Flushing Meadows for the second time in his career.

The Russian had already produced one of the most impressive resurgences of the tournament, recovering from two sets to one down to defeat Learner Tien in the previous round after also eliminating third seed Felix Auger-Aliassime. Now, after another strong performance against Blockx, Khachanov is back in the US Open semifinals and will face either Alexander Zverev or Botic van de Zandschulp.

The match began with both players holding their opening service games, but Khachanov soon established a clear advantage from the baseline. The Russian put pressure on Blockx with his heavier groundstrokes and capitalized on a loose service game from the Belgian to secure the first break, before breaking again to move 5-2 ahead.

Blockx managed to create some late resistance as Khachanov served for the set, earning two break points and briefly threatening to extend the contest. The Russian, however, stayed composed under pressure and eventually closed out the opening set 6-2, taking the early advantage after a dominant start.

Blockx responded much better in the second set, holding serve comfortably and forcing Khachanov to remain patient. The Belgian moved ahead 5-4 and appeared to have a chance to level the match, but Khachanov refused to give him an opening. With Blockx serving at 5-6, the Russian finally found the breakthrough, breaking at the crucial moment before serving out the set to take a two-set lead.

The momentum remained with Khachanov at the start of the third set, although Blockx continued to fight despite receiving medical attention during the changeover. The Belgian held his opening service game after returning to court, but Khachanov soon created another opportunity at 2-2. When Blockx came forward on break point, Khachanov fired a backhand directly into his opponent's body, forcing the error and moving ahead 3-2.

That proved to be the final game of the match. Blockx was unable to continue and retired, bringing his remarkable US Open run to an unfortunate conclusion. The Belgian had already made history by becoming the first Belgian man to reach the US Open quarterfinals, having beaten Flavio Cobolli and Francisco Cerundolo on his way to the last eight. He had also revealed after his win over Cerundolo that he had been dealing with a sharp rib problem during that match and had come close to retiring.

The victory marks Khachanov's return to the US Open semifinals, four years after his previous run to the last four in New York. The Russian has now reached the semifinals at both the US Open and Australian Open during his career, and his latest run comes after entering this tournament outside the seeded positions and ranked No. 50.

The result also guarantees Khachanov's return to the Top 30, adding another significant reward to a resurgence that has seen him beat Felix Auger-Aliassime and Learner Tien before advancing past Blockx. He will now wait for the winner of Alexander Zverev and Botic van de Zandschulp, with a place in the US Open final on the line.