Pedro pair avoids Barca slip up
Real Madrid's astonishing 4-0 defeat to another Segunda B team Alcorcon on Tuesday had raised expectations that Cultural might surprise Pep Guardiola's weakened Barca, but that was never really on the cards.
Bojan Krkic's snaking run helped set up Pedro for the opener after 41 minutes, and another product of the Barca youth system, forward Jeffren, curled in a cross that left Pedro free to volley the second just after the hour mark.
The second leg is at the Nou Camp in two weeks time.
Earlier, three second division sides complicated the lives of their top-flight visitors by establishing first-leg advantages.
Rayo Vallecano beat last season's finalists Athletic Bilbao 2-0 with early goals from former Bilbao midfielder Nestor Susaeta and veteran striker Sergio Pachon.
Hercules came from behind to win 2-1 against Almeria and Celta Vigo overcame Tenerife by the same scoreline.
Joaquin earned 2008 winners Valencia a narrow 1-0 victory over Segunda B Alcoyano, and the 2007 and 2008 finalists Getafe beat la Liga rivals Espanyol 2-0 at home with goals from Juan Albin and Jaime Gavilan.
The last three first legs take place on Thursday.