Swiatek's retirement put a stop to her 14-match winning streak in Rome and cast doubt on her eligibility for the French Open.
Iga Swiatek, a two-time defending champion, retired from her Italian Open quarterfinal match against Wimbledon winner Elena Rybakina in the third set due to a right thigh injury.
After more than two hours of play, the number one-ranked Swiatek retired with the score tied at 2-2 in the third. Before Rybakina won the second set 7-6 (3), she won the opening set 6-2.
The contest took place in highly humid conditions from Wednesday evening to early Thursday morning.
The withdrawal put a stop to Swiatek's 14-match winning streak in Rome and prompted concerns about her eligibility for the French Open, where the main draw begins on May 28 and where the Polish athlete is the current defending champion.
Swiatek grabbed her right knee during the second set tiebreaker after changing directions a several times beyond the baseline. After the set, she took a medical break and departed the court, nearly in tears. Her upper right thigh was wrapped when she came back. After four more games, she announced her retirement.
"I saw something happen in the tiebreak, almost on the last point, but I didn't know how serious it was," Rybakina said. She started out extremely aggressively in the first two games, so I recognised that she wasn't really able to move all that much.
The powerful Rybakina has defeated Swiatek three times this year. Three of Swiatek's six losses in 2023 are attributable to this.
Jelena Ostapenko, who defeated Paula Badosa 6-2, 4-6, 6-3 to advance to her first clay-court semifinal since winning the 2017 French Open, will face Rybakina in the final.
Veronika Kudermetova of Russia will compete against Anhelina Kalinina of Ukraine in the other semifinal.