Novak Djokovic won't defend his ATP Finals title after ruling himself out Tuesday citing an injury, leaving the season-ending event without a member of the Big Three of men's tennis for the first time in 23 years.

Djokovic had qualified automatically for the ATP Finals but his withdrawal means Alex De Minaur and Andrey Rublev are confirmed for the eight-player tournament in Turin. They join Jannik Sinner, Alcaraz, Alexander Zverev, Daniil Medvedev, Taylor Fritz and Casper Ruud.