Atletico Madrid stars Diego Godin and Augusto Fernandez both suffered knee ligament injuries in Saturday's 2-1 defeat at Barcelona, the club have revealed.
Fernandez was substituted with 15 minutes remaining, with Atleti by then down to nine men after Godin followed Filipe Luis in being sent off.
Uruguay defender Godin had also suffered an injury early in the game, the club said in a statement on their official website.
The statement read: "Diego Godin has undergone radiological tests on Sunday, which confirmed the injury to his left knee.
"The Uruguay international suffered a sprain (Grade I) on the internal lateral ligament in his left knee.''
Midfielder Fernandez "suffered a partial tear of the medial collateral ligament in his left knee,'' another statement said.
No timescale has yet been put on either player's recovery.