Real Madrid have suffered a blow in their attempts to win the La Liga title after falling to a 1-0 defeat at Athletic Bilbao.
Aritz Aduriz's 16th goal of the season was enough to move his side up to eighth place, as well as leaving the door open for Barcelona to move to the top of the standings on Sunday.
From the first whistle, a crescendo of noise from the passionate San Mames support greeted Real, and they never quite settled during the opening stages as Bilbao looked to stamp their authority on the match.
As the first half reached the midway point, it was Bilbao who had the momentum, and on 26 minutes, they opened the scoring when Aduriz powered a header past Iker Casillas after meeting a Mikel Rico delivery.
The remainder of the opening period saw Real struggle to create any clear-cut opportunities, but after the break, Real were reinvigorated and only some last-ditch defending from Bilbao kept them ahead.
Bilbao hit back through Aduriz, who forced a comfortable stop out of Casillas, but it was Real who were in the ascendancy and goalkeeper Gorka Iraizoz ensured that the score remained the same with saves from Isco and Karim Benzema.
The tempo intensified as the match moved towards the final quarter, but after Iraizoz came out well to save from Cristiano Ronaldo, Bilbao almost doubled their lead when Aduriz's header struck the post.
Time was running out for Real, but with six minutes remaining, Gareth Bale almost scored a stunning effort from all of 50 yards, but his shot struck the post before the rebound was wasted by Javier Hernandez.
It was an effort that deserved more, but that was as good as it got for Real, who fall to their fourth away defeat of the campaign.