Real Madrid charged seven points clear at the top of the Primera Liga after a second-half strike from Ruud van Nistelrooy earned a 1-0 win at Athletic Bilbao on Saturday.
The Dutchman angled a powerful right-foot shot into the far corner of the net after 55 minutes to take his tally for the season to seven in the league.
The victory gave Bernd Schuster's side 35 points from 15 matches, seven ahead of Barcelona and Villarreal who both play on Sunday.
Earlier, Ronald Koeman's Valencia continued their poor run of form with a 0-0 draw at Osasuna.
The Dutchman decided to field a new-look side after last weekend's 3-0 home defeat by Bilbao but his tactical changes had little effect as Valencia turned in another laboured performance.
Valencia, who have won two of their last seven league matches and have failed to find the net in their last three, remain sixth, 10 points behind Real.