Lille captain Rio Mavuba could be sidelined for three months after tests revealed that he needs surgery on a knee injury.
The club's coach, Rudi Garcia, confirmed that Mavuba, who was ruled him out of France's squad for the World Cup qualifier in Spain later this month, would be operated on after suffering the injury during Lille's 2-0 Ligue 1 defeat against Rennes last Friday.
"He tested [the knee] today, but it was inconclusive," Garcia said. "He will undergo surgery and should be out of action for six weeks to three months."
Lille are struggling in both Ligue 1 and the Champions League, in which they are bottom of Group F after losing to BATE Borisov and Valencia.
The worst case scenario would be that Mavuba is out of action until the winter break, but he said: "I tell myself that I'll come back stronger and fresher."