Kim Clijsters could be in danger of missing out on The French Open after sustaining a knee injury at the German Open.
Former world number one Clijsters retired from her match in Germany after injuring her right leg in an awkward slide to the net during a third-round match against Switzerland's Patty Schnyder.
Clijsters failed to convert four match points before surrendering the match while leading 7-6 5-6.
The Belgian, who missed most of last season with a career-threatening wrist injury, said she was not sure exactly how the injury occurred but suspected it was the slide late in the second set, after which she had a sharp pain in her knee.
She said she would have to wait several days for a scan to see if she had damaged any ligaments.
