French Open Open Nadal announced the problem of muscle problem, preventing him from playing in Paris Masters last week, and an ankle problem forced him to quit the season.
"Unfortunately bowel problems in Paris last week, it has an issue about which looga ankle link needs to be removed from the operating room today," the 17-time Grand Slam winner and Twitter.
"I hope to play full-time next season."
American John Isner will hold the 32-year-old in London when the final will be held on Sunday. Kei Nishikori is also preparing to replace Argentine star Juan Martin Del Potro, who suffered a knee injury.
Meanwhile, Spaniard Nadal left Paris, meaning Djokovic, who came back to the first place in the world ranking. The Serbian has now become the first player since the ATP in 1973 to finish the year 1 and start the top 20.
"The return of what I've been through last year, is a great victory," said Djokovic. "Of course, I'm very happy, and I'm proud of it.
"Five months ago, if you told me, I would have been – I always believed, but it was unbelievable when I was considering the rank and way I played and felt a court."
After missing the second half of the 2017 season, because of the troublesome memory, Djokovic returned to the start of the year but the injury has again happened in the Australian Open and has decided to perform an operation.
They were fired on the French Open after the 20-year-old quarter-final round before committing a penalty.
Djokovic beat Nadal at Wimbledon in the semi-finals before completing the two-year Grand Slam Drought defeat by Kevin Anderson at the end of the game.
A few weeks later he beat Del Potro in the final to win the US Open and last month won the Masters championship in Shanghai Mats unbeaten.
"What's wrong with Novak's success this season is to slow down one of his great recovery in return, and it is an incredible comeback that would have been difficult to imagine six months ago," the chairman said. ATP and President Chris Kermode said.
"He is fully fit to return to the No.1 of the ATP Rankings and he'll have his own season."
Djokovic was released on Sunday when he lost 7-5 6-4 to Russia's Kharen Khachanov at the Paris Masters final.