Rafael Nadal withdrew from the Paris Masters shortly before his opening match against fellow Spaniard Fernando Verdasco on Wednesday, meaning he will lose the ATP number one ranking to Novak Djokovic.
Spaniard Nadal, who has not played since retiring injured in the U.S. Open semi-finals, cited an abdominal injury.
"The last few days I start to feel a little bit the abdominal, especially when I was serving," Nadal said.
"I was checking with the doctor and the doctor says that is recommended to not play, because if I continue the abdominal maybe can break and can be a major thing, and I really don't want that."
.@RafaelNadal explique son forfait pour le tournoi.
ROLEX PARIS MASTERS (@RolexPMasters) October 31, 2018
Rafael Nadal explains his withdrawal from the tournament. #RolexParisMasters pic.twitter.com/Z6kEvR2ZP5
At last year's tournament, Nadal reached the quarterfinals but then pulled out against Serbian qualifier Filip Krajinovic. Nadal has dealt with off-and-on knee problems for years and, given his injury record, the 32-year-old Spaniard prefers to be cautious.
At the U.S. Open in early September, he dropped the opening two sets against Juan Martin del Potro before retiring. He then skipped the Asia swing to recover, missing tournaments in Beijing and Shanghai.
"It has been a tough year for me in terms of injuries so I want to avoid drastic things," Nadal said. "Maybe I can play today, but the doctor says if I want to play the tournament, I want to try to win the tournament, the abdominal with break for sure."
Nadal did not say whether he will play at the season-ending ATP Finals in London, beginning November 11.
"I don't know. You know, I am very sorry but I cannot answer. I just go day by day, as I did all my tennis career," the 17-time Grand Slam champion said. "I would love to be in London of course. But the most important thing for me is to be healthy, be healthy and have the chance to compete weeks in a row. Something that I was not able to do this year, playing only nine events and retiring in two. So that's the real point."
The 32-year-old needed to beat Verdasco to hold Djokovic at bay but the Serb will now return to the number one spot regardless of how far he goes in Paris.
Djokovic, who returned to form by winning Wimbledon and the U.S Open titles this year, reached the last-16 in Paris by defeating Joao Sousa on Tuesday.
Nadal's withdrawal could put his participation at the ATP Tour Finals in London at doubt.
Canada's Milos Raonic has also pulled out of his second round match against Roger Federer with a right-elbow injury.
Federer has returned to Bercy event after a three-year absence, chasing his 100th career title after claiming the Swiss Indoors crown last week.
(With inputs from Reuters and AP)