Marseille midfielder Stephane M'Bia will be out for several weeks with a groin injury, depriving coach Didier Deschamps of one of his best players for the title run-in.
M'Bia limped off minutes into Saturday's League Cup final win over Montpellier.
''The news isn't good,'' Deschamps said Monday on the club's website. ''I don't think he will come back before mid-May.''
The Cameroon midfielder could potentially miss five of defending champion Marseille's seven remaining league games. The French league ends on May 29.
Marseille is two points behind leader Lille, but has a game in hand and can go top if it beats Nice on Wednesday. Marseille then plays Auxerre, title rival Lyon, Brest, and then Lorient on May 15.
The 24-year-old M'Bia is a crucial player in Deschamps' team because he can play both as a holding midfielder, his favored role, or fill in at centre-half as he did toward the end of last season.
Deschamps may be forced into reshuffling his defense as left-back Taye Taiwo could also be ruled out for a while.
The Nigeria defender faces a possible suspension for his expletive-laced chant following his team's 1-0 victory over Montpellier on Saturday.
Taiwo, who scored the winning goal, took the microphone after the game and joined in with Marseille fans singing an offensive song aimed at bitter archrival Paris Saint-Germain. The two clubs have a long history of animosity and violence.
The French league will submit Taiwo's case to the football federation's National Ethics Council. Taiwo has apologized.
''He shouldn't have done (it), it's very silly,'' Deschamps said. ''What he said wasn't good. He realized that and felt very sad about it. He didn't realize what proportions it would take.''
Deschamps said that because other players, such as former Barcelona striker Samuel Eto'o have done similar things in the past, Taiwo should not be made an example of.
''I don't want to minimize it, but you shouldn't exaggerate,'' Deschamps said. ''It's happened to others. That's not an excuse but Samuel Eto'o took the mic (celebrating) Barca's league title and spoke (in offensive terms) about Real Madrid.''
