Rafael Nadal is aching to play at the 2014 ATP World Tour Finals, but the Spanish tennis superstar is still unsure whether or not he will be fit enough to compete in the tournament in London on Nov. 9.

Nadal said in an interview this week that he is still struggling to regain his form due to appendicitis, which was the main reason why he suffered an early exit at the Shanghai Rolex Masters last week when he lost to Feliciano Lopez in his first match.

"I am sad because I didn't have the chance to compete, I was in a big process of antibiotics for a week-and-a-half and the body goes down, you need time to recover to get your top physical performance," Nadal told Sky Sports.

Nadal, who is still struggling to regain his rhythm following a long layoff due to a wrist injury, decided to delay surgery and is currently taking antibiotics. He said that immediate surgery is still not yet out of the question.

"I have had weeks of injury so it was not an easy season for me at the end, I have to do the surgery but I have to find the right moment," Nadal added. "I need to see how things go and how my body accepts the antibiotics, so after all the things that have happened over the last few weeks -- let's see."

The 14-time Grand Slam champion insisted that he is looking forward to competing in London, but he admitted that he is still unsure if he will be fit enough to play at a high level.

"I will try to do my best (to be in London) but I cannot say, I do not know a hundred percent," Nadal said.

Nadal, who has not won a Grand Slam title this year, fell to No. 3 in the ATP world rankings after losing to Nick Kyrgios in the fourth round of the 2014 Wimbledon and failing to defend his title at the 2014 U.S. Open because of the wrist injury.

In his first tournament after a long layoff, Nadal also failed to impress, losing to Martin Klizan in the quarterfinals of the 2014 China Open in Beijing earlier this month.

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