Sevilla have confirmed Samir Nasri suffered a hamstring injury in their match against Sporting Gijon on Saturday.
The 1-1 away draw saw Jorge Sampaoli's side drop down to fourth in the table, with the on-loan Manchester City star - who has made an impressive start to his Sevilla career - having to be replaced at half-time.
Reports in Spain suggest Nasri will miss Wednesday's home Champions League game against Dinamo Zagreb as a result and is a major doubt for the crucial LaLiga match against Barcelona on Sunday, also at Ramon Sanchez Pizjuan.
"Tests reveal Samir Nasri has suffered damage to his left hamstring," the club said in a statement on Monday.
"He will undergo further tests to determine how long he will be out."
Forward Wissam Ben Yedder (ankle) came off in the second half of the match at Sporting and is also set to miss the Dinamo game.