Van Nistelrooy played with Ronaldo at both United and Real Madrid.
"He would have been about seventeen. Back then he said that he'd be the best player in the world," recalled Van Nistelrooy.
"He is vain and not just a little.
"In the dressing room he made sure that he looked quite sleek, styled from head to toe. He was also a really nice guy in the locker room. Always cheerful, joking, full of jokes. A great colleague. I did not perceive him as arrogant.
"He was very open to advice at Manchester. Like the others I have also talked to him."