All change as Nadal prepares for Wimbledon

"Practically everything changes, from the first ball which is the service," Rafael Nadal said in an interview with Reuters.

"The service on grass is much harder to return. From there, you have to play as aggressively as possible, try to make your shots fast, simply gain the initiative in the point as quickly as you can," he said.

Time, however, conspires against him with barely a fortnight between the French Open final last Sunday and the start of Wimbledon.

"It's a bit tight, especially if you get to the final at Roland Garros. There's hardly time to rest and it comes on top of you very quickly," he said.

"I've been playing for practically two months on clay courts and playing lots of matches. That Roland Garros and Wimbledon should be so close means I can't rest for a moment and that's not good."

Nadal warmed up for the French Open with victories at Monte Carlo, Rome and Barcelona, his only defeat coming to big rival Roger Federer in the Hamburg final.

The 21-year-old from Majorca, however, believes he has the complete game needed to succeed on other surfaces and with youth on his side, if he continues to improve can win the other grand slam tournaments.

Nadal also told Reuters he does not believe any of his fellow professionals sets out to take banned drugs, with positive tests the result of errors they made taking medicines or supplements.

Clay game

"My goal is always the same, to keep improving. I'm young, I'm only 21... this helps you to see things calmly and try to go on improving," said Nadal, who is playing the pre-Wimbledon grasscourt tournament at Queen's this week.

Nadal said he does not target particular tournaments or a position in the ranking, believing success will follow from working towards perfection.

"Everything (I do) is focused towards the same thing. If I manage to become a better player then I'll have more chances of winning on all types of surface and have more chances of being number one," he said.

"On clay, the game is more complete, because you have to run and you have to place the ball accurately, you have to play aggressively, you have to know how to defend, you have to know how to attack at a given moment.

"Here (on grass), well, if you serve very well and you're a player who is more or less daring, things become a lot easier.

"Of course, the more assets you have and the more complete you are (as a player) that helps a lot more."

Historically, the top players have either won the Australian Open, Wimbledon and US Open but failed to lift the French Open crown, or vice-versa, with only a select few succeeding at all tour grand slams.

Federer, whom Nadal beat in the last two French Open finals, has won the other three but finds the Spaniard an ever bigger barrier at Roland Garros.

In view of some cases of doping in tennis, Argentine Guillermo Canas's recent return from suspension and in response to being asked whether he looks at such players differently, Nadal said: "As I wouldn't do any of that, I think that neither would the other players.

"In this case of Guillermo Canas, I always believed he was a clean player and straight.

"Any little error, any small oversight makes for a result as if you'd taken dope when really it was simply that you'd taken a pill for a cold."