Bernd Schuster's side came into the game with a four-point advantage over bitter rivals Barcelona and surprise package Villarreal, who both play on Sunday.

This game was played amid a passionate derby atmosphere in San Mames and Real were forced to weather the storm as Athletic piled on the pressure in the first 10 minutes.

The Basque side dominated the opening exchanges and buoyed by their vociferous home support, had the visitors on the back foot early on.

And they could have gone ahead after eight minutes, when David Lopez latched on to a ball from deep, but was denied by a wonderful save from Iker Casillas.

Having weathered the early pressure and managed to stay on level terms, Madrid carved out a decent opportunity on 11 minutes, when Raul turned neatly in the box and forced Daniel Aranzubia into a smart save with a powerful angled drive.

The keeper, in for the injured Gorka Iraizoz, then picked himself to deny Robinho on the rebound.

The Brazilian was then put through by compatriot Julio Baptista, but failed to control the ball and the chance was lost.

Baptista, starting for the second week in a row following a decent performance against Racing Santander and a brilliant display in the Santiago Bernabeu trophy against Partizan Belgrade in midweek, was a constant threat and saw his header blocked on 21 minutes.

At the other end, David Lopez shot wide and also saw a free-kick comfortably saved by Casillas as the home side threatened.

Casillas came to his side's rescue once again on 28 minutes to push out a close-range header by Joseba Llorente in the clearest chance of the game so far.

Eight minutes later, Sergio Ramos did put the ball in the net, but the Real defender saw his effort correctly ruled out for offside.

The visitors started brightly after the interval and went ahead on 55 minutes, when Van Nistelrooy beat Aranzubia with a powerful shot which was hit virtually straight at him and the keeper should really have saved.

Nevertheless, Real looked good for their lead at this point and could have gone two ahead on 68 minutes, but Raul was denied by a last-ditch challenge from Lertxundi Koikili.

Four minutes later, Robinho struck a low drive against the post from outside the area as Madrid probed once again.

But Athletic were still in the game and Casillas was the hero again on 75 minutes, when he got down quickly to push away Llorente's drive from an acute angle.

Guti, rested for Real's crucial Champions League game against Lazio on Tuesday, then came on for the injured Van Nistelrooy and Arjen Robben replaced Robinho in the closing stages as the champions looked to sew up an important victory.

They did so despite some late Athletic pressure to move seven points clear at the top of the Primera Liga.