MADRID: Former men’s tennis world number one Rafael Nadal’s long-awaited return after an agonizing six-month knee injury battle has been put off because of a stomach infection he revealed on his Twitter and Facebook accounts on Tuesday.

The 26-year-old Spaniard—who hasn’t played since his shock second round exit to 100th-ranked Lukas Rosol at Wimbledon in June—had been due to play in a six player exhibition tournament in Abu Dhabi this week ahead of his return to the ATP circuit at Doha from December 31.

He was due to join world number one Novak Djokovic and US Open champion Andy Murray among others at the three-day event.

“I am really sorry but I cannot compete this year in Abu Dhabi,” wrote the seven-time French Open champion and presently ranked number four in the world.

“Everything was ready and I was really eager to return to competition, but the doctors have forbidden me to participate in Abu Dhabi because of a viral infection of the stomach which has provoked a fever.”

Nadal, an 11-time Grand Slam title winner, has been plagued by knee injuries throughout his career, a legacy of his all-action style.

But earlier this week he shrugged off any fears that despite falling to number four in the world rankings, he is no longer a threat to Djokovic, Murray and world number two Roger Federer.

“I haven’t forgotten how to play. I have played over 600 ATP matches and I have spent two years without playing. My feeling is good. I won Roland Garros and those emotions are still me,” he said.

“The doctors say the knee is fine and that is great news for me. I still feel something, it’s not perfect.”

Nadal insisted he is not bitter over his recent experiences.

“I have accepted it as normal, as part of my career, part of my job. It’s another challenge. All I can do is try. ” he told marca.com.