Berlin, 25 May 2024 (dpa/MIA) — Novak Djokovic has admitted to form and fitness concerns heading into Sunday's start of the French Open where the title holder could lose the world number one spot to Jannik Sinner.

Djokovic, who turned 37 earlier in the week, is yet to win a tournament this year and went out in the Geneva semi-finals against Czech player Tomas Machac, 6-4, 0-6, 6-1.

The Serb spoke of stomach problems but also agreed that he is not going into the Paris grand slam, where his first opponent is French wildcard entry Pierre-Hugues Herbert, in the best overall shape.

“Of course I am worried. I haven't been playing good at all this year,” the ATP quoted Djokovic as saying.

"You have to accept it. I don’t consider myself a favourite there. I’m going to take it match by match and see how far I can go.”

Djokovic decided to play in Geneva via a wildcard after an early exit the previous week at the Rome Masters.

“It was good that I could come here and play more than one match. I played three,” he said.

“I just need to feel better. I just hope I can be fit and ready and prepared for Roland Garros.”

The 24-time grand slam winner has 2,000 points to defend in Paris from his 2023 title, much more than Sinner who went out in the second round last year.

Djokovic needs to reach the Roland Garros semis to retain the top spot, if Sinner goes out early again, the ATP said.

Australian Open champion Sinner can become the first Italian player atop the world rankings but his form is also unclear following hip problems and he has admitted "not to expect miracles" from him.