Andy Murray and Novak Djokovic hold up their trophies after the men's singles final at the ATP World Tour finals tennis tournament at the O2 Arena in London, Britain, Nov 20, 2016. [Photo/IC]

But Murray refused to let the chance to slip, wrapping up the victory with a solid service and a tortuous 14-minute final game.

"I'm very happy to win and to be world number one is very special," Murray said. "It's very special playing against Novak in a match like this."

Djokovic said after the match, "Andy is definitely number one in the world. He deserved to win. He is the best player.

"In the decisive moments, I wasn't able to come back. I played better late in the match but it wasn't enough."

Murray takes home $2,391,000 in prize money while Djokovic wins $1,261,000.

"It's a very special day, playing against Novak in a match like this," said Murray. "We've played in Grand Slam finals, Olympics and matches like this - it's been a tough rivalry. I've lost many of them, but I am happy to have got the win today to clinch the year-end No. 1. It's very special, it's something that I never expected."