The former Manchester United striker fears he will miss out on going to the World Cup with Holland unless he can secure first-team football.
Injuries have limited him to just one start and three substitute appearances so far this season, but even a fully fit Van Nistelrooy may struggle to win a place among a forward line packed with Galacticos.
Adios: Ruud van Nistelrooy looks set to leave Spain
Coach Manuel Pellegrini also has to juggle the talents of Cristiano Ronaldo, Kaka, Raul, Karim Benzema and Gonzalo Higuain.
Van Nistelrooy said: 'I want to play. I still haven't spoken to ManuelPellegrini because I'm still recovering (from injury) but when I amready I will speak to him.
Galaxy of stars: Real Madrid boss Manuel Pellegrini watches over training with Cristiano Ronaldo (left) and Marcelo (right)
'If I do not get minutes, that will give me a reason to leave in January.
'My intention is to play at the World Cup with Holland. If I do not play (club football), that will be impossible because I need to be able to prove that I can still play at the level I did a few months ago.'
Spurs boss Harry Redknapp showed interest in signing the 33-year-old in the summer but were concerned by long-standing knee problems and his high wage demands. He earns about £90,000 a week at the Bernabeu.
However, reports in Spain say Spurs and City are both watching developments with interest. Liverpool have also been linked with the former PSV Eindhoven striker, but it is understood that Rafa Benitez is not keen.
Van Nistelrooy missed the majority of last season with a serious knee injury and picked up a thigh problem in his first game back after nine months out. His Madrid contract expires at the end of the season.
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