Real restored a 4-point lead over their bitter rivals with a 2-0 victory against Osasuna on Sunday, and Van Nistelrooy is glad to visit Nou Camp on top.

"It was important to win so that we can go to the Nou Camp with a four-point advantage," said Van Nistelrooy, who scored the first of two goals against Osasuna.

"With this we can go there to attack, without fear. It will be a tough game and it is better to go secure in the knowledge that whatever happens we will remain leaders."

Barca also registered an impressive 3-0 victory at Valencia on Saturday to keep the chase with the holders, but the Catalans suffered a major blow after losing Lionel Messi to injury.

The Argentine prodigy scored a superb treble in last season's corresponding fixture, and Real keeper Iker Casillas is relieved he will not face the World Player of the Year contender.

"The loss of Messi is very important for Barca because he's a key player in fantastic form, but they have recovered (Samuel) Eto'o who has proven beyond doubt he is well again," said Casillas.

Eto'o marked his comeback from a lengthy layoff by scoring twice at Mestalla, the Cameroonian also found the net against Stuttgart in last week's Champions League win.