Unseeded Russian Karen Khachanov advanced to the US Open semifinals on Wednesday at Arthur Ashe Stadium after Belgian 28th seed Alexander Blockx retired in the third set due to worsening lower back and rib injuries, ending a run that still secures Blockx a top-30 ranking debut.
Physical Toll and Retirement at Arthur Ashe Stadium
The physical toll of a punishing fortnight finally caught up with Alexander Blockx during his quarterfinal clash on Wednesday. Playing in his first Grand Slam quarterfinal, the 21-year-old Belgian found himself trailing 6-2, 7-5, 3-2 before signaling that he could no longer continue against Karen Khachanov. Blockx had entered the match already battling a rib injury that had hampered him since the Round of 16, where he defeated Francisco Cerundolo while playing through pain.
Throughout the match, the compounding injuries dictated the rhythm of play. Blockx struggled visibly with his serve during the opening frame, resulting in two early breaks for his opponent. Between sets, he requested a medical timeout to treat an issue with his left foot rather than his torso. As the second set wore on, torso pain returned. By the third set, lateral movement had become nearly impossible. Following another break of serve that put Khachanov ahead 3-2, Blockx informed the chair umpire of his decision to retire, bringing a quiet end to his breakthrough run in New York.
Khachanov Returns to the Semifinals in New York
For Khachanov, the victory marks a return to the final four at Flushing Meadows for the first time since 2022. Entering the tournament unseeded at a Grand Slam for the first time since Wimbledon in 2018, the 30-year-old Russian navigated a demanding draw before meeting Blockx. Ranked 50th in the world, Khachanov acknowledged the complicated emotions of winning via retirement after controlling the court.
Karen Khachanov stated via sports.yahoo.com that it was a mixed feeling, noting that from one side he felt he was dominating from the beginning before starting to feel like his opponent was struggling more and more. He added that since his opponent was suffering, he did not want to scream come on or something like that, as he wanted to keep the energy still there, while wishing him a definitely speedy recovery and expressing that he was super happy to be in the semifinals and exclaimed come on.
The win elevates Khachanov into his third career Grand Slam semifinal, following previous runs at the 2022 US Open and the 2023 Australian Open. His experience on the second weeks of major tournaments proved decisive as Blockx’s physical reserves dwindled.
Milestones and Ranking Breakthroughs for Blockx
Despite the abrupt finish, Blockx leaves New York with significant career milestones. By reaching the quarterfinals—becoming just the first Belgian man to reach the US Open quarters—he surpasses previous benchmarks for young Belgian contenders. His run included a notable upset over third-seeded Felix Auger-Aliassime in the preliminary rounds and a gritty fourth-round victory over Francisco Cerundolo.
The tournament performance guarantees a major rankings jump. Blockx climbs into the top 30 for the first time in his career, landing provisionally at 26th in the live rankings after starting the end of 2025 at 117th. Back home, tennis officials are monitoring his recovery closely with upcoming Davis Cup fixtures against Austria approaching in Vienna.
Next Up in the Semifinals
Khachanov advances to face the winner of Wednesday evening’s primetime quarterfinal clash between top-seeded Alexander Zverev and Dutch veteran Botic van de Zandschulp.
