Fulham midfielder Mahamadou Diarra could be ruled out for the majority of the season due to a cruciate ligament injury.
Diarra suffered the injury making his return to international duty for Mali after not playing for his country for over a year.
The full extent of the injury is expected to be revealed next week but manager Martin Jol fears that the midfielder could be unavialable for at least three to five months.
"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," said Jol.
"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."
Diarra joined Fulham in February of this year, making 11 appearances for the club last season.