Inaki Williams scored twice as Athletic Bilbao beat Real Sociedad 2-0 in La Liga's Basque derby on Saturday.
La Real had the chance to tighten their grip on fourth place after Villarreal stumbled to a 2-1 home defeat by relegation-battling Real Valladolid, but fell short at a fiery San Mames.
Real Sociedad goalkeeper Alex Remiro made good saves from brothers Nico and Inaki Williams, before the latter broke the deadlock when he stabbed home from a corner.
La Real complained Inaki had handled the ball after taking a swing at it and mishitting it, but VAR showed he did not.
Athletic goalkeeper Unai Simon made a fine double save to deny Ander Barrenetxea and then Take Kubo, to keep his team ahead.
Inaki smashed home his second goal after 70 minutes, driving into the box and rifling past Remiro from a tight angle.
Alexander Sorloth should have pulled one back for the visitors but inexplicably slammed over the bar from point blank range.
Barrenetxea followed suit with another huge miss when completely unmarked in the box late on, leaving Athletic fans laughing in the stands at their luck.
Los Leones celebrated with their fans at the end, the victory making amends for their recent Copa del Rey semi-final exit against Osasuna.
Real Sociedad's defeat meant Quique Setien's Villarreal's surprise loss against Real Valladolid was not as costly as it might have been.
Selim Amallah struck for the visitors in the second minute and Jawad El Yamiq doubled their lead after Villarreal's Samu Chukwueze had a goal disallowed for offside.
Etienne Capoue pulled one back for the Yellow Submarine but it was Valladolid, provisionally 14th and five points above the relegation zone, who came closer to scoring in the final stages.
Villarreal goalkeeper Pepe Reina made some fine saves to keep Valladolid at bay, after their new coach Paulo Pezzolano was sent off for complaining about Capoue's strike.
The hosts, who beat champions Real Madrid 3-2 last weekend in a thriller at the Santiago Bernabeu, felt they deserved more.
"The result does not show what happened in the 90 minutes, I think Villarreal were superior in every aspect to Valladolid," said Villarreal's Dani Parejo.
"We leave sad and disappointed with the result, but we feel football has been unjust to us."
