World No. 1 Aryna Sabalenka advanced to the semifinals of the U.S. Open without hitting a shot, as quarterfinal foe Marketa Vondrousova withdrew from the tournament Tuesday with a knee injury.

Vondrousova hurt herself during a practice open for public viewing, ESPN reported. Video showed the Czech Republic native wince and lean over for several moments after hitting a shot. She did not hit another, and she was seen in tears on the side of the court, according to ESPN.

“I am sorry to announce that I have to withdraw from my quarterfinal match this evening due to a knee injury,” Vondrousova said in a statement. “I tried my best to take the court today, but during the warm-up I felt again my knee, and after consultation with the tournament doctor decided not to risk aggravating the injury.

“I appreciate all the support this tournament and apologize to the fans who were looking forward to the match. I had an amazing time here in New York and can’t wait to be back next year.”

“So sorry for Marketa after all she’s been through,” Sabalenka wrote on Instagram. “She has been playing amazing tennis and I know how badly this must hurt for her. Take care of yourself and I hope you can recover quickly.”

The development happened a few hours before she was set to face Sabalenka for a spot in the semis — and it means that the Belarusian star will face No. 4 seed Jessica Pegula on Thursday in a rematch of last year’s final.

Pegula swept another Czech player, Barbora Krejcikova, 6-3, 6-3 earlier Tuesday in New York.

Sabalenka, 27, hasn’t dropped a set this tournament. She won her third Grand Slam title when she beat Pegula 7-5, 7-5 last year and has yet to add to that total in 2025. Pegula, the home favorite as a native of New York state, is vying for her first Grand Slam.

Vondrousova, 26, had her career highlight in 2023 when she became the first unseeded woman to win Wimbledon. This was set to be her first quarterfinal match at a Grand Slam since the 2024 French Open.

–Field Level Media