After limping off Real's loss to Juventus last week, the player earlier said that he'd be out for about two months. However, further tests confirmed that he will need a surgery keeping him out form much longer.

"Following an exploratory arthroscopic operation on Wednesday, it was determined that Ruud van Nistelrooy had a partially torn meniscus in his right knee," Real Madrid stated on their official website.

"Real Madrid's medical staff, and American expert Richard Steadman decided to surgically repair the damaged knee, by which he will miss between six and nine months."

The news will come as a massive blow to Real coach Bernd Schuster, as Van Nistelrooy is the only club striker available within the squad.

The 32-year-old scored 63 goals for Los Merengues since he joined the club from Manchester United in the summer of 2006.

It is worth noting that the knee problem is the same injury which kept the former Holland international out for seven months in 2000 when he was playing for PSV Eindhoven.