Neymar’s first-half penalty was enough to give Barcelona their first win at Real Sociedad’s Anoeta in eight attempts to end a run which lasted almost a decade.
The Brazilian converted from the spot after being brought down by a clumsy Aritz Elustondo challenge in a high-intensity match which was short on opportunities for both sides.
The last time Barca had triumphed at the San Sebastian stadium was in May 2007, and they were fortunate to escape with a draw in the league clash earlier in the campaign.
Jasper Cillessen and Lucas Digne both started in favour of Marc-Andre Ter Stegen and Jordi Alba while Ivan Rakitic was selected ahead of Denis Suárez, but there were no surprises as Neymar returned to line-up with Lionel Messi and Luis Suarez up front.
Carlos Vela unexpectedly started for La Real despite a knee concern and will help Willian Jose up top for the Basques.
The first effort came in the 11th minute when Mikel Oiarzabal cut inside after some slack passing from Barca but he could only blaze his effort over the bar.
Neymar opened the scoring in the 21st minute after converting the penalty he won following a clear and clumsy foul by Elustondo, La Real will have been frustrated after an opening period of the game where neither side had found their rhythm.
Two minutes later Messi was felled by Yuri on the byline and the Real Sociedad defender kicked the ball, albeit rather gently, at the Argentine who did not react too kindly, but as he did throughout the half – the referee calmed things down and opted not to produce any cards.
The home side grew in confidence as the half went on as they started to retain possession and play at a higher tempo – Illarramendi’s effort from just outside the area was deflected wide in the 36th minute, and from the resulting corner Willian Jose got a clear header but could not direct it towards Cillessen’s goal.
Lionel Messi picked up a yellow card just before the break for time-wasting over a free-kick, which summed up an odd and rather uneventful first half.
There will be concern for Blaugrana fans as Andres Iniesta was subbed off at half time, with later reports he was ‘suffering discomfort’ but no further information was disclosed as Andre Gomes played the second half.
Neymar could and should have doubled Barca’s lead five minutes into the second period but he was foiled by Geronimo Rulli who stood tall in a one-on-one situation to make a confident block.
The hosts had a penalty appeal of their own turned down soon after, but Xabi Prieto’s effort hit Lucas Digne’s arms from close-range and any award would have been extremely harsh.
However, despite Eusebio’s men increasing the pressure and enjoying plenty of possession it was the visitors who carried the greater threat – ten minutes into the half Neymar cut inside and curled a right-footed effort inches wide of Rulli’s far post.
The game was then blighted by an awful officiating decision as Real Sociedad’s David Zurutuza was inexplicably called offside from a free-kick when he was two yards the right side of the defensive line, the decision made all the more controversial as he had a clear run at goal.
The home side had their tails up and Yuri was the next to threaten – flashing a shot-come-cross across the goal but it evaded all the incoming forwards and flew past the far post.
Just after the hour mark, the ever-lively Neymar was booked for a perceived dive in the penalty area – Suarez’s effort was initially blocked by Rulli with the ball spilling loose to the former Santos forward but he appeared to throw himself to the ground under minimal contact.
Messi came close to extending his magical recent run of scored free-kicks, but his effort flew inches over the bar to keep the tie alive.
However, both the Argentine star (for blocking a quick free-kick) and Neymar (for a late challenge) can perhaps count themselves fortunate not to receive second yellow cards, with the home fans bringing out the white hankies for referee Jose Luis Gonzalez.
Luis Enrique’s side held on for a hard-fought win in a tight match which they shaded to end an unwanted record and make a decisive step towards the Copa del Rey last four.
GOALS: Neymar pen ‘21
Real Sociedad: Rulli, Illarra, Iñigo Martinez, Prieto (Canales ’76), Carlos Vela (Juanmi ’71), Willian Jose (Concha ’80), Elustondo, Zurutuza, Oyarzabal, Yuri, Raul Navas
Subs: Ramirez, Granero, Hector Hernandez, Gaztanaga
Barcelona: Cillessen, Sergi Roberto, Umtiti, Pique, Digne, Rakitic (Denis Suarez ’68), Busquets, Iniesta (Gomes ’46), Suarez, Messi, Neymar
Subs: Masip, Turan, Mascherano, Alcácer, Alba
Referee: Jose Luis Gonzalez