Barcelona's decade-long hoodoo at the Estadio Anoeta has continued for another season, as they slipped to a surprise 1-0 defeat at the hands of Real Sociedad this evening.
The Catalan giants, who had earlier seen Atletico Madrid and Real Madrid make up some ground in the title race, came unstuck in the Basque Country to make it five defeats and two draws here in seven visits.
Barca remain at the top of the table, although their lead has now been cut to just three and four points on Atletico and Real respectively after going three league games without a win.
It could have been a different story entirely had Munir El Haddadi, in for the suspended Luis Suarez from the off, taken a big chance that fell his way just three minutes in.
The forward profited from a lucky deflection to find himself through on goal, but Geronimo Rulli made himself big to keep out the shot from just a few yards out.
That proved to be an early turning point in the game, as Sociedad were soon up the other end where Mikel Oyarzabal made the breakthrough following a fine right-sided cross which he directed into the top corner.
Barca struggled to create any real chances as the half wore on, being made to work particularly hard to break down a home side containing six players in the backline at times.
All that hard work very nearly counted for little when Neymar's pull-back found Arda Turan in a central position 32 minutes in, only for the midfielder to shoot straight at a grateful Rulli between the sticks.
After seeing their opponents enjoy their best passing spell of the game, Sociedad won back possession and sprung a quick counter which culminated in full-back Alberto De La Bella being played in on goal down the left.
Despite having time to get a clean shot away, De La Bella took far too long to compose himself and in the end his tame shot was blocked aside with ease by the visitors.
That proved to be it in a first half containing just three shots of note, forcing Luis Enrique to change things around at the break by bringing on Andres Iniesta for the largely ineffective Rafinha.
Iniesta almost made an immediate impact when sending a ball over the top for Lionel Messi, which the Ballon d'Or holder swung at rather wildly perhaps expecting to see the offside flag raised.
The half-time sub was taking matters into his own hands, asking serious questions of Rulli when getting in a long-range drive which looked destined for the top corner before being helped on its way over.
Barca were growing increasingly frustrated as the contest transpired, with Neymar's near miss from a free kick 25 yards out the closest they came to drawing level prior to the hour mark.
Rulli did have to be alert to deny Messi 15 minutes from time, however, after Gerard Pique's knockdown fell nicely for the forward to fire away his first attempt on target.
An underwhelming Messi had another decent opportunity to snatch a point at the death, but he headed the ball right down Rulli's throat when picked out unmarked in the box.
The final act of the match saw Iniesta once more denied by the Royals' inspired keeper, whose save in added time sparked scenes of joy at a venue that Barca have now failed to win at in the past nine years.
