Real Madrid coach Carlo Ancelotti admits David Alaba may have suffered an ACL injury.
Alaba broke down during victory over Villarreal.
Ancelotti said afterwards: I haven't spoken with him. The medical report says he's ruptured his cruciate ligament. We're really sad about it because he's another player we'll lose. I've never had three of my players get cruciate injuries inside three months.
"What the team has to do is exactly what it's been doing so far, with all the injuries we've had. We've done more than what anyone believed we were capable of.
"Despite the problems, this team fights, digs in, plays some great football and shows extraordinary commitment. That's the only way to fill in for all the guys who are out injured. We'll see what can be done in the coming days."