Defending champion Novak Djokovic has pulled out of the ATP Finals because of an "ongoing injury".

The 37-year-old Serb, who has won a record seven titles at the event, had already qualified as the sixth best player on the ATP Tour this season.

"I was really looking forward to being there, but due to ongoing injury I won't be playing next week," Djokovic wrote on social media.

"Apologies to those who were planning to see me. Wishing all the players a great tournament. See you soon."

Djokovic, who has won a record 24 Grand Slam men's singles titles, indicated last month that competing in the tour's year-end finals was not a priority.

"I am not chasing ATP Finals, I am not chasing the rankings," Djokovic, who beat the current world number one Jannik Sinner to win last year's title, told Serbian reporters., external

The former world number one reiterated he wants to focus on the Grand Slams as he looks to prolong his career.

It means his next tournament is likely to be the Australian Open, which starts on 12 January.

In Melbourne, Djokovic will be aiming for an all-time record 25th major singles title - putting him clear of Australia's Margaret Court - and a 100th tour-level trophy.

His withdrawal from the ATP Finals means the eight-man field for the Turin tournament is set.

Norway's Casper Ruud, Australia's Alex de Minaur and Russia's Andrey Rublev, who looked set for an exciting battle this week for the final two places, have qualified as a result.

Italy's Jannik Sinner, Spain's Carlos Alcaraz, Germany's Alexander Zverev, Russia's Daniil Medvedev and Taylor Fritz of the United States had already clinched their spots.

The tournament takes place in the Italian city between 10-17 November.