Karen Khachanov advanced to the US Open semi-finals on Wednesday after Belgian player Alexander Blockx retired from their quarter-final match with the Russian leading 6-2, 7-5, 3-2. Khachanov, ranked 50th in the world, entered the tournament unseeded, marking his first Grand Slam appearance without a seeding since Wimbledon in 2018.

This marks Khachanov’s third appearance in a Grand Slam semi-final, having previously reached the last four at the 2022 US Open and the 2023 Australian Open. His upcoming semi-final opponent will be either top-seeded Alexander Zverev or Dutch player Botic van de Zandschulp.

Khachanov’s journey to the quarter-finals included notable victories over third-seeded Canadian Felix Auger-Aliassime and American 14th seed Learner Tien. In his match against Blockx, Khachanov observed that his opponent appeared to be in considerable physical discomfort. “I saw really that he was suffering all over his body,” Khachanov said.

Blockx, who set a milestone as the first Belgian man to reach the US Open quarter-finals, has been dealing with injuries during the tournament. He revealed that he was close to retiring during his fourth-round victory against Francisco Cerundolo due to a rib injury. In Wednesday’s match, Blockx took medical timeouts to receive treatment for a foot injury and apparent lower back pain that affected his performance throughout the contest.