Ronaldo always told us he would be the world's best, reveals Van der Sar

It’s a game Real cannot afford to lose as they defend their title.

Van der Sar said: “Cristiano told all the United lads that he wanted to become the best player in the world and he was going to make sure he would be.

“He was always the first one in at the training ground. He worked harder than any other player.

“He was training hard, he would stay on the training ground for more free kicks when the others were finished.

He would go back in the gym and he would work on his physique all the time. He has become so strong, has so much pace, because he has invested all his time and energy in that.

“He still does not go out much, he does not smoke and he does not drink.”

The Dutch goalie, who retired 16 months ago, went on: “He is now able to make the difference in the biggest matches at ­international level – like he did against Ajax.

“One of the Ajax ­defenders had a bit of a fight with him. I said to the guy sitting next to me in the stand: ‘Oh dear, don’t upset him. When he gets angry, Cristiano is at his very best’.

“Five minutes later he scored two great goals and demolished Ajax. That is what he is capable of these days. He is different from ­Barcelona’s Lionel Messi, but definitely as good as Messi, who seems to be liked by the public more than Cristiano.

“But Cristiano is a fabulous guy too. He has the odd sulk in a match but he is a winner – thanks to the valuable lessons he learned in ­Manchester.’’

Real have started the ­domestic season poorly, and coach Jose Mourinho will ­demand a return to top form on Sunday night.