Chelsea boss Graham Potter says it "doesn't look positive" for Armando Broja after the striker suffered a serious-looking knee injury during a friendly against Aston Villa.
The Albania international, 21, collided with Villa defender Ezri Konsa during a match in Abu Dhabi, before holding his right knee and screaming in pain.
Broja was taken off on a stretcher.
"I think he got caught up with their player and the ground," Potter told Chelsea's website.
"It doesn't look positive at the moment, but it is too early to say. Fingers crossed, but it is an awkward one.