Real Madrid striker Ruud van Nistelrooy will be out of action for around six weeks after having arthroscopic surgery for a problem with his right ankle, the Spanish champions said on Wednesday.

The 31-year-old should be back in time to face Barcelona at the Bernabeu on May 7, the club said in a statement on their Web site (www.realmadrid.com).

The Dutch international has missed Real's last four matches in all competitions with a persistent swelling around the ankle joint.

Van Nistelrooy, who has scored 12 league goals for Real this term, will miss up to seven of the side's remaining 10 matches as they close in on a second consecutive Primera Liga title.

They lead second-placed Barcelona by seven points.

His absence will give little-used reserves Gonzalo Higuain, Roberto Soldado and Javier Saviola the chance to shine alongside the team's other first-choice striker Raul, for much of the title run in.