Saint-Etienne winger Max Gradel is expected to miss the rest of this season and the start of next with a ruptured cruciate knee ligament.
The injury happened during a training session while Gradel was on international duty with the Ivory Coast.
Gradel has already had a consultation with a surgeon and the initial prognosis is that he will be out for up to six months.
Saint-Etienne already lost Jeremy Clement this month after he broke his leg during the 4-0 win against Nice and will be forced to continue their Champions League push without two key players.
