Erick Cabaco and Borja Mayoral scored in the opening 20 minutes to give the hosts a comfortable lead at half-time.

Brazilian midfielder Philippe Coutinho pulled a goal back for Barcelona with a late penalty.

The defeat came just three weeks after Barca had thrashed Levante 5-0 in the league, with Lionel Messi scoring a hat-trick.

Messi was one of several omissions from Ernesto Valverde's much-changed side.

The second leg will take place at the Nou Camp on Thursday.