Barcelona failed to hit a shot on target in the first half for the first time this season in Sunday's 1-1 draw with Real Sociedad.
Luis Enrique's side took 41 minutes to muster an effort in a dreadful opening 45 minutes at Anoeta, in which they also failed to attempt a cross from open play.
The champions did not test Geronimo Rulli in the home side's goal until the 51st minute, when Neymar's free-kick was parried wide of the post.
They also managed just 48 per cent of the possession throughout, making it the first time all season in which they have had less of the ball than their opponents.
A draw means they are six points behind Real Madrid heading into the Clasico next week, but it would have been worse but for more clinical finishing from Lionel Messi.
The Argentina star found the equaliser with his only effort on target, meaning he has now scored five goals from his last seven goal-bound attempts in all competitions.