Jannik Sinner says he still has areas where he can improve next year after winning the ATP Finals for the first time on Sunday to cap a near-perfect season for the world's top-ranked player.

The 23-year-old Sinner beat Taylor Fritz 6-4, 6-4 at the season-ending event in Turin for the eighth title of a remarkable season that began with his first Grand Slam triumph at the Australian Open.

He followed that up with a second Grand Slam victory at the U.S. Open in September after becoming embroiled in a doping controversy for twice testing positive for traces of the steroid clostebol six months earlier.