(CNN) -- Kim Clijsters could miss the French Open after picking up a foot injury while on Fed Cup duty with Belgium.
The former world number one has been told she faces six weeks on the sidelines after sustaining the injury in her singles match against Maret Ani of Estonia on Saturday.
An initial x-ray showed no signs of damage but an MRI scan revealed a muscle rupture in her left foot.
The second Grand Slam event of the tennis calendar begins in Paris on May 23 and Clijsters now faces a race to be fit for the tournament.
"We saw a lot of fluids around the muscle, and the doctor said it had a small rupture in it," Sam Verslegars, Clijsters' physio, told the Fed Cup's official Web site.
"We're going to try and recover properly, which means not trying to speed things up, because if her injury gets chronic, then we've got a real problem. We'll go easy with the rehab and then see how long it takes."
Justine Henin also picked up a knock in Belgium's 3-2 victory over Estonia. The world number 24 was nursing a broken finger and lost her singles match with Kaia Kanepi on Sunday.
"All the things that happened this week, including my injury, Kim's injury -- I've not had the best preparation," Henin said. "It's been a difficult week."