Djokovic equals Sampras's record of six year-end No 1 trophies

This was the sixth year he finished as world No. 1, having earlier done it in 2011, 2012, 2014, 2015 and 2018.

Among past players, only Pete Sampras has managed to finish six years on top of the rankings which he did between 1993 and 1998.

Djokovic is currently participating in the ATP Tour Finals at The O2 Arena here.

"I'm very happy," Djokovic told ATPTour.com on Sunday. "It's been a strange year for all of us with a six months' gap for all of us. We restarted the season in August, and I continued where I left off before lockdown and had a terrific run. I'm very pleased with the way things went."

Djokovic says he felt mixed emotions as the world is reeling from corononavirus pandemic.

"Obviously I am super proud of it, but I have mixed emotions because of what is going on in the world. I can't be ignorant to that, although I have achieved one of the biggest goals in sport. I feel for many people in the world going through hardship and my heart goes out to them."