Marseille have confirmed that their captain Bafetimbi Gomis will be out for four to six weeks due to a knee ligament injury.
The on-loan Swansea striker, 31, went off injured in the second half of Marseille's 3-2 defeat at Nantes on Sunday, shortly after getting his second goal of the game.
Gomis is now set to sit out his team's home match against rivals Paris Saint-Germain on Feb. 26 as well as their Coupe de France round-of-16 meeting with Monaco on March 1.
Marseille will be short of forward options in the absence of this season's third top goalscorer in France, who has netted 16 of their 33 Ligue 1 goals so far.
Gomis had helped Marseille climb to sixth in the standings and his coach Rudi Garcia left no doubt as to the significance of the injury.
"The most serious thing is not even the defeat -- it's the injury to Bafe," Garcia was quoted as saying by L'Equipe.
Gomis hurt his knee in a collision with Nantes defender Diego Carlos a few minutes after getting his 16thleague goal of the season. That total matches his previous best tally in Ligue 1, which he achieved once with both Saint-Etienne and Lyon in the past.