Novak Djokovic wary of Rafael Nadal's French Open challenge

Novak Djokovic believes that Rafael Nadal will be favourite to retain his title at the French Open next week.

The Spaniard has been crowned champion of the Roland Garros on six occasions throughout his career and even though Nadal has dropped down to number three in the rankings following a third-round knockout in the Madrid Open last week, Djokovic is confident that the 25-year-old will be a force in Paris.

"It is a grand slam where Nadal is always the top favourite and Federer and other players are able to win it," said Djokovic. "It's going to be interesting to see who comes out on top."

Meanwhile, Djokovic has claimed that he may not compete at the Madrid Open next year due to the controversial blue clay surfaces.