Rafael Nadal [Images] has never lost at the French Open and has won 88 of his last 89 matches on clay, yet feels he still has plenty of room for improvement.

The Spaniard on Sunday become the first man since Bjorn Borg in 1980 to win a hat-trick of Roland Garros titles, wrecking Roger Federer's [Images] bid to complete his collection of Grand Slams.

"For me to have three Grand Slams [from the French Open] is a dream," said the world number two who now has an 8-4 advantage over Federer, including a commanding 6-1 record on clay.

• Images: Celebrities at the French Open

"When I go on court, I'm not 100 percent I'm going to win. I know I can lose."

Comparing his three titles in Paris, he added: "The first year was very emotional because it was the first. Second year was very emotional because I came back after injury. This year, I am very happy because I played my best tennis here."

The 21-year-old took his record to 21-0 at the claycourt Grand Slam after handing world number one Federer a heartbreaking 6-3, 4-6, 6-3, 6-4 defeat.

The Wimbledon, US Open and Australian Open champion badly wanted to win here to become only the third man after Don Budge and Rod Laver to hold all four majors at the same time.

Instead, he had to bow to the superiority of a player who now wants to extend his run of form to other surfaces.

By picking up his fifth title in 2007 Nadal felt all his hard work had paid off, especially as he had an eight-month period from last July when he did not reach any final.

MORE COMPLETE

"The most important thing for me is to improve my tennis, feeling I am playing well," he said.

"If I'm improving then I'm going to have my chances to win more Grand Slams, especially off clay. Last year I won a lot of matches without playing very well," added the Spaniard.

"I feel a better player this year... I am more complete. I know I can go to the net and have better chances than before. I can play a little bit more aggressive with my forehand and I've improved my backhand. But I have more to do."

Nadal proved last year he had the game to adjust to the slicker surfaces when he surprised many, including Federer, by reaching the Wimbledon final.

Despite that achievement, he has been playing down his chances of replicating the feat.

"I'm now going to play on grass and this is going to be a difficult tournament," he said.

"Playing a final again will be very difficult. You're talking about a surface that is, obviously, not my favourite.

"But I want to do my best and get into Wimbledon with the best possible preparation. And if I don't succeed, I'll go back home happy because I did what I could."