Barcelona's terrible record at the Anoeta continued and they were fortunate to escape with even a point as Real Sociedad were denied a clear winner in their 1-1 draw.
Not since 2007 have Barca won in San Sebastian and they were thoroughly outplayed by their hosts as they extended their unbeaten run to eight home games against Luis Enrique's side, who now trail La Liga leaders Real Madrid by six points ahead of next weekend's El Clasico.
Willian Jose's opener was cancelled out by an equaliser from the largely anonymous Lionel Messi shortly after, but Sociedad had a legitimate winner ruled out when substitute Juanmi was incorrectly ruled offside as he finished with 14 minutes to go.
Given La Real's impressive record, it was no surprise to see them start with a spring in their step as they pinned Barca back for virtually the entire first half.
David Zurutuza's header over was an early warning from Sociedad, who harried their visitors high up the pitch and pushed men forward at goal-kicks to force Marc-Andre ter Stegen to go long.
There was also a clear tactic to test a perceived weakness against full-back Jordi Alba in the air, with Xabi Prieto twice going close with headers from left-wing crosses, the second of which was directed wide when he was all alone six yards out.
Former Arsenal striker Carlos Vela was the next to go close when he latched on to a ball over the defence and fired wide having taken himself away from goal with his initial poor first touch.
Alba's difficult evening looked to have ended prematurely through injury when he showed anguish after Prieto landed on him, while Gerard Pique also signalled to the bench that he needed replacing having hurt himself sliding in on Mikel Oyarzabal.
Both were okay to continue, though, and their team were at least able to muster an effort on goal as Luis Suarez drove well wide with a snapshot.
However, it was the first time all year Enrique's team had failed to register an attempt on target in the first half and the Barca boss tried to turn the tide by replacing Ivan Rakitic with Denis Suarez at the break.
Neymar saw an early second-half free kick pushed around a post but the hosts finally went in front in the 53rd minute through a route-one attack.
From goalkeeper Geronimo Rulli's long ball, a Zurutuza flick on was latched onto by Vela ahead of Javier Mascherano and while his shot was saved by Ter Stegen, Willian Jose's header from the back of the penalty box found its way past Pique on the line.
The centre-back's reaction showed he knew he should have kept the ball out, yet the fact he had received strapping to the foot injury moments earlier may have excused Pique somewhat.
La Real's joy proved short-lived and their lead lasted only six minutes. Neymar skipped beyond Raul Navas on the left and steered a pass across the box where Messi finally came alive, taking one touch before lashing in an equaliser.
Both sides pushed for a winner but it was the hosts who had the better chances and did score a second with 14 minutes to go, only to be robbed by the offside flag.
Vela cut back on to his left from distance to fire against the woodwork, with the ball bouncing down just on the line, and substitute Juanmi reached the rebound to tap home a simple finish.
The referee's assistant immediately raised his flag even though replays showed he was clearly kept onside by Pique.
Vela then hit the post with another effort from range but the visitors held on to claim a point that was scarcely deserved.