World number one Ashleigh Barty retired with injury from her second-round match against Magda Linette at the French Open.
The 2019 champion had strapping on her left thigh and struggled with her movement, losing the first set 6-1.
Barty, 25, left the court for a medical time-out before retiring at 2-2 in the second set.
World number 45 Linette – who had never beaten a top 10 player – faces Tunisian world number 26 Ons Jabeur next.
Following Naomi Osaka’s withdrawal on Monday, Belarusian third seed Aryna Sabalenka is the highest-ranked player left in the women’s draw.
Also on Thursday, Ukrainian fifth seed Elina Svitolina enjoyed a more straightforward win as she beat American Ann Li 6-0 6-4.
American fourth seed Sofia Kenin had a tougher battle in the first set against compatriot Hailey Baptiste but came through to win 7-5 6-3.
Barty had managed to come through the first round on Tuesday despite needing lengthy treatment on her left hip during the match.
After that win, the Australian admitted she was “not quite 100%” and on Thursday arrived on Court Philippe-Chatrier with strapping on her left thigh.
Holding back in her movement, presumably to avoid pain, Barty was broken to go 3-1 down and Linette took her chance to strike.
The 29-year-old broke again and went on to claim the first set before Barty called the trainer onto the court and eventually went inside to receive treatment.
After a lengthy break, the 25-year-old looked much sharper and held serve twice but must have been suffering as she eventually turned to the umpire to call the match to an end.