Real Sociedad strengthened their hold on third place with a convincing 3-1 Basque derby victory over Athletic Bilbao on Saturday.
Elsewhere Yangel Herrera's late lob earned Girona a 2-1 win over Sevilla, piling more misery on Jorge Sampaoli's side, 17th.
Imanol Alguacil's Real Sociedad, aiming to qualify for the Champions League for the first time since 2014, moved six points behind leaders Barcelona who face Real Madrid in the Spanish Super Cup on Sunday.
La Real are only three points behind Los Blancos, albeit having played an extra game than the top two, currently in Saudi Arabia.
Alexander Sorloth, Takefusa Kubo and Mikel Oyarzabal's goals helped the hosts beat their rivals at the Reale Arena.
Oihan Sancet struck for Athletic, who had Yeray Alvarez sent off in the second half for a foul on the superb Kubo.
"(I feel) joy, goals are important for people that play up front," Oyarzabal told Movistar.
"The most important thing was everything else -- winning, the way we did it, we were better in almost all the game."
Ernesto Valverde's team have had a good start to the season themselves and defeat leaves them eighth, just two points behind the top four.
Sorloth netted his fourth goal in four consecutive league games to break the deadlock after 25 minutes.
The Norwegian stayed onside to control Igor Zubeldia's header, sent back into the danger area, and then finished with aplomb.
Their second goal was brilliantly worked, with veteran playmaker David Silva winning the ball back and feeding Kubo.
The Japan international nutmegged Dani Vivian and then fired confidently beyond Unai Simon to double his team's lead.
Sancet pulled one back three minutes later with a smart finish beyond Alex Remiro, to keep Athletic in the game.
However Alvarez was dismissed for felling Kubo in the area -- a decision which Athletic vehemently contested -- and Oyarzabal netted calmly from the spot, his first goal since returning from injury at the end of December.
The Spanish striker, who ruptured a knee ligament in March, replaced Sorloth early in the second half after he suffered a knock -- the one negative note for Alguacil's side.
"For the good of everyone, if that is a penalty it shouldn't be a red card," complained Athletic defender Oscar de Marcos.
"The game was a nice one for the fans and after that, it disappeared."
- Sampaoli struggles -
Earlier Sevilla fell to defeat at Girona and could drop into the relegation zone on Sunday depending on other results.
Tanguy Nianzou sent Sevilla ahead in the 13th minute but it was the French defender's mistake which allowed Herrera to pounce in the final stages.
Cristhian Stuani levelled at the start of the second half, with Girona, 11th, on top and they deserved their win with Sevilla only mustering two shots on target.
Sevilla forward Rafa Mir fired over in the final stages but with the game heading for a draw, Herrera punished him with his 88th minute winner.
Nianzou, who had already got away with one ball lost in a dangerous area, was robbed on the edge of his own box and Herrera did the rest with an exquisite finish.
"Individual errors (cost us), we do a lot of things well but like that, it's very hard," Sevilla midfielder Ivan Rakitic told Movistar.
"We have to understand that we can't mess up, this can't happen.
"Everyone individually has to find their pride, this cannot happen again."
Rayo Vallecano won 1-0 at Real Valladolid, while Osasuna beat Mallorca by the same score at El Sadar.
On Sunday, Atletico Madrid visit Almeria, aiming to move back fourth with a victory.