Sky's the limit for Nadal

"He is so young. But he is like some players like Connors, Muster, who like to compete, to fight," said Costa who retired in 1998.

"I remember when I started with Rafael three years ago, he was 15 or 16, I asked him if he would sign on for a career like mine or one like [2003 French Open champion] Albert Costa."

But Nadal said he wanted more: "He already wanted to do something special, he wanted to be a player that everybody remembers and he is doing this."

So can Nadal still improve?

"He works a little bit on his serve, volley also and now his slice. But you know when you keep winning from the baseline it's hard to change. He will do it maybe this year. He is going to play Queen's. He rents an apartment in London. He will spend the week before Wimbledon practicing on grass. He is thinking about it and he wants to do it well on grass also."

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