David Villa struck just after halftime to lift champions Barcelona to a laboured 1-0 home win over his former club Sporting Gijon in La Liga on Wednesday.
Andres Iniesta had a dominant Barca's best chance of the first half but Cuellar palmed his powerful low shot away for a corner.
The home side controlled possession without ever looking like extending their lead and survived a spell of late pressure to secure the win.
With four matches played, Barca have nine points, one behind arch-rivals Real Madrid, who beat Espanyol 3-0 on Tuesday, and level with Valencia, who can make it four wins out of four with a home victory over Atletico Madrid in Wednesday's late kickoff.
Villa's first goal for Barca in Milan friendly
Messi hat-trick gives Barca Super Cup win
Champions League final ban for Fletcher
David Villa flying high for Spain
Wounded Barca, Man U eye Champions League boost