Fulham fear Mahamadou Diarra could be ruled out for the majority of the season with a serious knee injury.
Martin Jol has revealed Diarra damaged his knee ligaments on international duty earlier this month with Mali.
Diarra was forced to miss last weekend's win over West Brom and Jol has confirmed the former Real Madrid man required some form of surgery and would miss at least another three weeks.
However, if it transpires he has damaged his cruciate ligament, he could be out for up to five months.
Jol, who was expecting to learn the true extent of the damage next week, said: "There's a little piece of cartilage floating in his knee, so we have to operate that in any case, and that can be three or four weeks.
"But if there is damage to his cruciate ligament, for example, it will take a lot longer. It will take him three, four, five months at least."