Iga Swiatek suffered an injury scare ahead of defending her French Open title when the World No 1 was forced to pull out of her Rome Masters quarter-final against Elena Rybakina. The 21-year-old retired from Wednesday's clash against Wimbledon champion Rybakina with the match delicately poised at one set apiece and 2-2 in the decider. During the second-set tiebreaker, Swiatek grasped her right knee after shifting directions a few times behind the baseline. Close to tears, she took a medical timeout after the set and left the court. When the Pole returned, her upper right thigh was bandaged and, after four more games, she retired. The retirement ended Swiatek’s 14-match winning streak in Rome and raised questions over her fitness for Roland Garros where the main draw starts May 28. "We're checking it [the injury]," tweeted the three-time Grand Slam winner. "During the second set I got a thigh injury. The diagnostic is in progress. More info in the following days. Will keep you updated." It was the third time that the big-serving Kazakhstani has beaten Swiatek this year, which accounts for three of her six losses in 2023. “I saw something happen in the tiebreak, on almost the last point but I didn’t know how serious it is," said seventh seed Rybakina. "The first two games she started really aggressive so I understood that she couldn’t really move that much.” Rybakina’s last-four opponent will be Latvia's Jelena Ostapenko, who beat Spaniard Paula Badosa 6-2, 4-6, 6-3 to reach her first semi-final on clay since winning the 2017 French Open. The other semi-final will feature Veronika Kudermetova of Russia against Ukraine's Anhelina Kalinina.