Despite coming into the match on a four-game winless run in all competitions, the hosts made a lively start, but could well have fallen behind on 17 minutes when Frenkie de Jong beautifully slipped in the returning Robert Lewandowski.
Dani Vivian’s long pass over the top caused a mix-up between Jules Koundé and Marc-André ter Stegen, but Álex Berenguer could only help the ball wide under pressure from the Germany goalkeeper, who was making his 350th club career appearance.
The home fans were clearly in a mischievous mood, throwing fake money onto the pitch in reference to Barça being charged in the week over alleged historical payments to try and influence refereeing decisions.
Iñaki Williams drew a great save from Ter Stegen down to his left, before Raúl García – in for the suspended Oihan Sancet – crashed a header against the bar from Berenguer’s resulting corner.
Former Barça boss Valverde threw on Iker Muniain for García to alter the complexion of the contest, but that change had little impact until the diminutive forward’s whipped shot forced Ter Stegen into a brilliant save on 79 minutes.
Athletic thought they had equalised when Williams was played in and finished with aplomb, but the goal was chalked off after hitting Muniain’s left arm in the build-up, before a frantic passage of play in the dying minutes somehow saw Barcelona survive.