PARIS, Oct. 31 (Xinhua) -- Current world No. 1 Rafael Nadal announced his withdrawal from the ATP Paris Masters 2018 due to an abdominal problem, sending Novak Djokovic back to the top spot in the ATP rankings for the first time in two years.

"The last few days I started to feel a little bit the abdominal, especially when I was serving," Nadal told a news conference.

"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," he added.

"I don't know if we can talk about a real injury. I can talk about a pain that bothers me

every time that I serve. It would not be fair to say it's a real injury today but what is sure, if I continue it will be a real injury. So that's the point," said Nadal.

Nadal was expected to make his return in Paris after retiring in the U.S. Open semifinals due to a knee injury. He was scheduled to face his fellow Spanish Fernando Verdasco in the second round on Wednesday afternoon, but made his decision to withdraw from the competition just prior to the duel.

"It has been a tough year for me since that moment in terms of injuries so I want to avoid drastic things.

"Maybe I can play today, but the doctor says if I want to play the tournament and try to win the

tournament, the abdominal will be with break for sure. It will be not fair and not good for me and for anybody to go inside the court knowing that probably the full tournament will not be possible to play.

"Of course I am not happy, but of course I have to accept and stay positive," Nadal pointed out.

Already qualifying for the ATP Finals in mid November, Nadal emphasized the importance of health when asked about his prospect of playing in London.

"As I said hundreds of times, I would love to be in London. But the most important thing for me is to be healthy and have the chance to compete weeks in a row. It's something that I was not able to do this year, playing only nine events and retiring in two," he said.

Djokovic arrived in Paris knowing that he needs to advance further than the Spaniard for regaining the top position. The four-time winner beat Joao Sousa in Tuesday's second round.

The Serbian has not been world No. 1 just since the 2016 Paris Masters.