Elena Rybakina stops playing during first set of quarterfinal vs. Iga Swiatek at Cincinnati

MASON, Ohio (AP) — Elena Rybakina stopped playing during the first set of her quarterfinal match against Iga Swiatek at the Cincinnati Open on Thursday night.

With the No. 2-ranked Rybakina serving at 1-4, 40-40, she took a medical timeout to have trainers address her left ankle area and retired from the match moments later.

“Of course I feel not the greatest,” Rybakina said. “It's painful to walk. We'll know more tomorrow when we have the MRI. It's been bothering me for a long period of time but felt like I had it under control.”

After aggravating the injury during the second set on Thursday, she spent several minutes speaking with trainers before returning to the court. She decided to call it quits after she was unable to put full weight on her leg while attempting a serve.

“It was feeling OK before (Thursday’s) match,” Rybakina said. “Unfortunately one wrong movement and something happened.”

With top seed Aryna Sabalenka losing Thursday night to Sara Bejlik, the 27-year-old Rybakina could have risen to No. 1 in the rankings by reaching the final.

Swiatek, the defending champion, will face American Jessica Pegula in the semifinals. She has reached at least the semifinals in each of her last four appearances in Cincinnati. Swiatek beat Rybakina in the semifinals in Cincinnati last year.

“Not the way you want the match to end,” Swiatek said. “She didn't look good, obviously. Then she wanted treatment and I wasn't sure if she was going to be back or not. She's walking normally now. I felt really sorry for her but hopefully it's nothing serious and she's going to be ready for the U.S. Open.”

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