Real Madrid with a 1-0 victory at the new San Mames Stadium.
The hosts, who defeated Espanyol in midweek, showed no signs of a cup hangover and went ahead courtesy of Aduriz’s fine header midway through the first half.
And although the visitors upped the tempo in the second half and hit the woodwork through a fantastic Gareth Bale effort, Bilbao were worthy of a victory that blows the title race wide open.
It means that Barcelona will take over at the top of La Liga should they beat Rayo Vallecano at the Nou Camp on Sunday.
26’ – GOAL! Athletic Bilbao 1-0 Real Madrid: A lovely ball into the box from Mikel Rico picks out Aduriz but his header is even better, powered into the top corner to give Casillas no chance.
28’ – IRAIZOZ SAVE: A great ball in from Isco is volleyed on goal from Bale but the keeper saves well with his legs. Flag was up for offside anyway.
72’ – GOOD SAVE IRAIZOZ: Benzema plays in Ronaldo but an outstretched hand from the keeper palms the ball to safety.
76’ – ADRUIZ HITS POST: Another header from Adruiz clips the outside of the post from Susaeta’s assist.
83’ – BALE HITS THE BAR: It’s a fantastic effort from the winger who spots Adruiz off his line only to see his lob come back off the underside of the bar.
Madrid have now lost two of their last 20 meetings with Bilbao..
Aduriz scores his 18th goal of the season in all competitions.
Toothless Real set to lose top spot: having drawn at home last time out, there was little change in Real’s urgency. They failed to carve out many openings and that will be a worry for Carlo Ancelotti with Barca set to replace them at the summit.MAN OF THE MATCH
Aduriz (Athletic Bilbao) A close call between the striker and teammate Williams but his brilliantly taken 18th goal of the season was the difference between the sides.
Athletic Bilbao: Iraizoz 7, Iraola 6, Balenziaga 7, Etxeita 6, Gurpegui 7, Benat 6, Mikel Rico 7, De Marcos 6, Muniain 6, Aduriz 8, Williams 8. SUBS: Toquero 6, Susaeta 7, Guillermo 6.
Real Madrid: Casillas 6, Varane 6, Pepe 6, Carvajal 6, Marcelo 6, Illaramendi 6, Kroos 6, Isco 7, Bale 6, Benzema 5, Ronaldo 6. SUBS: Hernandez 6, Lucas Silva 6, Jese 6.