Diego Costa was taken off on a stretcher during Wolverhampton Wanderers match against Tottenham Hotspur on Saturday after landing awkwardly.
The 34-year-old Spanish striker jumped with Spurs' man Oliver Skipp, but his landing caused what seemed to be a serious knee injury.
Costa was removed from the field of play after 27 minutes of action, and replaced by Raul Jiminez.
His likely long-term absence is another blow for Julen Lopetegui's side, who are continuing to have problems scoring goals this season. The first half finished scoreless at Molineux.