(Corrects headline to show it was a retirement, not a walkover)
By Janina Nuno Rios
NEW YORK, Sept 9 (Reuters) - Karen Khachanov advanced to the U.S. Open semi-finals on Wednesday when Alexander Blockx retired trailing 6-2 7-5 3-2, as the Russian reached the final-four stage in Flushing Meadows for the first time since 2022.
Blockx, who became the first Belgian man to reach the U.S. Open quarter-finals, was already carrying a rib injury into the match and was visibly hampered by further physical issues.
He wore a brace on his right ankle and had his thigh wrapped, with the 21-year-old also calling for the trainer during the contest.
The 28th-seeded Blockx battled on despite his discomfort but was unable to match Khachanov as the 30-year-old continued his resurgence in New York, before eventually calling it a day after one hour and 38 minutes.
Blockx, who upset fifth seed Flavio Cobolli in the third round, had already hinted at his physical issues, admitting he came close to retiring during his match against Francisco Cerundolo in the fourth round.
"Today my body just gave up," Blockx told reporters.
"I had it really difficult physically already. Against Francisco, I was on the verge of retiring, and today just kept getting worse."
"I was still feeling my rib a lot. My leg. Then in the second set, I blocked a nerve in my back, which yeah, was even worse to move."
World number 50 Khachanov will return to a Grand Slam semi-final for the first time since reaching the last four at the Australian Open in 2023.
"I was preparing really well for that match up, it's not easy because I feel I was dominating then I felt he was struggling more and more," Khachanov said on court.
"He was suffering, but I wanted to keep the energy there. I wish him a speedy recovery but I'm super happy I'm in the semis."
The former world number eight, who had not played a major with a ranking this low since 2017, had already knocked out third seed Felix Auger-Aliassime and 14th seed Learner Tien on his way to the last eight.
He will face either top seed Alexander Zverev or Dutchman Botic van de Zandschulp in the semi-finals.
(Reporting by Janina Nuno Rios in New York; Editing by Stephen Coates and Muralikumar Anantharaman)
