Even though the 'King of Clay' has triumphed at Roland Garros nine times in the last 10 years, he has, rather uncharacteristically, struggled on clay this season.
Nadal's woes on clay began last month when he lost to Novak Djokovic in the semi-final of the Monte Carlo Masters.
He was then knocked out in the third round of the Barcelona Open before bouncing back by making it to the final of the Mutua Madrid Open, where he failed to win the title as he was beaten by world number three Andy Murray.
Nadal was unable to get back to his winning ways at the recently concluded Rome Masters as he was defeated by Stan Wawrinka in the quarter-finals.
"When I say I don't know what's going to happen, I really don't know what's going to happen," Nadal, who has a 66-1 French Open record, said during his pre-match press conference. "That doesn't mean that I don't have confidence (in) myself to try to be ready for it. I have to think that I am ready for it. It) is a tournament that I love."
Nadal will face Quentin Halys in the first round of the French Open on Tuesday.