"I think things are looking much better," he said. "It was tough at the beginning of the year but I have definitely bounced back these last few months.
"I'm feeling where I want to be shortly before a really important stretch of tournaments. That starts here in Paris, so I feel good about my chances.
"I'm moving so well, and I haven't any problems after playing a lot of matches. I know I can beat him (Nadal). All the chances are here for me to win it."
The women's event looks wide open following the shock retirement of defending champion Justine Henin on the eve of the tournament.
Speaking at Roland Garros on Saturday, the Belgian confirmed: "I don't think I will ever come back. I think that it's important to just to move on."
Her exit has left Maria Sharapova at the top of the rankings, but the Russian is at her least comfortable on clay and pulled out of her scheduled Italian Open semi-final against Jelena Jankovic last week because of a calf strain.
It's quite amazing to be 21 years old and have somebody tell you that it's the only Grand Slam that you haven't won
However, Sharapova expects to be fit to challenge for the one major title that still eludes her.
Sharapova will play fellow Russian Evgeniya Rodina in her opening match on Monday or Tuesday.
"To be quite honest, it's quite amazing to be 21 years old and have somebody tell you that it's the only Grand Slam that you haven't won," she said.
"I've always said it, it's the toughest one - it's always going to be in my career - to win. But that's why I'm here. I've said it every single year. I love the challenges."
The top seed should be pushed by Serbians Ana Ivanovic and Jelena Jankovic, as well as 2002 champion Serena Williams.
"It's probably the best preparation I've had since 2002. I feel like I've played so many clay court tournaments," said Williams.
"I just really am feeling like a real clay-court player, which, I think, is important for me. I'm really comfortable out there on the clay, so it's great."
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