Montpellier fear Geoffrey Dernis could be missing for up to six weeks after suffering a knee injury on Saturday.
The midfielder picked up the knock during a 1-0 victory over Brest.
He netted what proved to be the winning goal in that contest, but was forced off nine minutes into the second half.
Initial reports suggest that the 31-year-old has suffered ligament damage and will be sidelined for the foreseeable future.
Dernis is set to be sent for scans on Monday, allowing Montpellier to put a more definitive timescale on his recovery.
They are, however, expecting to be given bleak news by the club's medical staff.
"It is a worrying injury," said coach Rene Girard.
"His injury was the black spot of the match against Brest."