Novak Djokovic is a five-time ATP World Tour Finals champion and has also won multiple titles leading up to the event: five in Beijing, three in Shanghai and four in Paris. He says the indoor season final push is the reason for his success in London.
"I can say from my perspective that I always try to really take the last drop of energy, whatever is left in my body," he told press in London. "I've been very fortunate to really play some great tennis in the fall [such as] Paris and Shanghai."
He also attributes his recent string of victories to the location of the ATP World Finals itself: London.
"I like playing in the O2 Arena. I like the surface conditions," he said. "I guess the fact that every match is against a top-eight player in the world, there is no, I guess, easy matches...
"It's best-of-three. It's more intense. You have to be really on top of your game. I guess that's something that extracts that type of motivation and inspiration for you to perform well."
Even though he didn't win any of the indoor events coming into the tournament this year—where he is competing with Andy Murray to reclaim world No. 1—he has begun finding his form during the tournament.
"I've been playing better and better as I proceed in the [Finals]," the Serbian said.
Djokovic will play against Kei Nishikori in the semifinals.