By Julien Pretot
PARIS (Reuters) - Rafa Nadal believes he can finish the year as world number one after dropping to fifth in the rankings on Monday, changing places with David Ferrer, the man he beat to win the French Open for a record-extending eighth time.
Due to the ATP's 12-month rolling ranking system that awards no points for defending a title, Nadal had nothing to gain for reclaiming the Roland Garros crown he won last year.
The 12-times grand slam champion, however, now has almost nothing to lose until the end of the season after a knee injury sidelined him for the last five months of 2012.
"There are still six months ahead of us," Nadal told reporters.
"I could be number one again if I continue at that level and if I'm not injured. But this is not 100 percent sure."
After last year's French Open, Nadal reached the quarter-final in Halle and the second round at Wimbledon before injury ended his 2012 campaign.
This means he has just 90 points to defend until the end of the season.
"To be number one in this era, you need to play during the whole season," he said.
"You have to play during the whole season and do well, because the other players are very competitive. They're going to be there.
"I need to keep winning a lot of points if I want to have any chance to be number one at the end of the season."
Nadal heads to Wimbledon in search of a third title, but having decided to skip this year's Halle tournament, his preparation for the grasscourt grand slam will be far from ideal.
"I will check all my body and I hope to be ready for Wimbledon," said Nadal.
"I don't play a tournament before Wimbledon so that's not the ideal situation before a grand slam like Wimbledon, which is on grass and with conditions that are very different.
"But if you can make it a few rounds, then the situation changes."
His uncle and coach Toni Nadal told reporters: "He can win Wimbledon but others can, too, like (Novak) Djokovic, (Roger) Federer or (Andy) Murray. At Wimbledon, many can beat him because the ball goes faster and is harder to control."
Nadal came to Roland Garros with doubts hanging over his knee and his ability to win yet another title, but came through the grueling fortnight unscathed.
"Today I was able to compete with 100 percent, so that's fantastic," he said after beating Ferrer on Sunday.
"It's true that in Barcelona my feeling was very negative about my knee. So I am still going week by week, day by day. I will take a look after here.
"That's what we are going to do over the next few days, try to do the right things and to be ready for Wimbledon."
As well as being injury free, the Spaniard says that he is now more relaxed - a potentially deadly combination for his opponents.
"I am taking everything a little bit more relaxed," he said. "Before I wanted to practice every day a lot to be 100 percent sure that I am ready, but that's not possible anymore.
"Hopefully it will be possible in the future, but not today. I think mentally I have accepted that situation.
"When you get more experience on tour, you probably don't need to practice as much as you do when you were a junior or when you are 19 or 20."
(Editing by Toby Davis)