Nadal, who will end the year ranked number one in the world after winning the French Open, Wimbledon and the U.S. Open, is suffering from tendinitis in his left shoulder but said he will return to training this week.
"I am not worried at all about London," the Spaniard told a news conference at Paris's Bercy sports hall on Monday.
"It was not an easy decision (to pull out of the Paris Masters) because Paris is a special city for me, but I have played all the season's Masters and grand slams."
"I will be back to practice soon (...). Before next Sunday."
Despite already having the year-end No.1 spot in the bag, Nadal will be determined to end the year in style in London's Docklands after a miserable performance when the tournament was staged there for the first time last year.
"I'm gonna do all in my hands to play well there," said Nadal, who lost all six sets he contested in the spectacular O2 Arena last year. "It's my goal to improve the image of last year in London."
However, Nadal hinted that his priority was to make sure he begins next year 100 percent fit, unlike last year when he withdrew from the Australian Open mid-match against Andy Murray.
"If I have an injury now, it will be difficult to play at the beginning of the season next year," he said.
The ATP World Tour finals start on Nov. 21.
