Britain's Andy Murray beat five-time champion Novak Djokovic to win his first ATP World Tour Finals title and end 2016 as the world number one.
Murray held serve to prevent the five-time champion from restoring parity in the second set, and while Djokovic was able to delay the celebrations with a hold of his own before staving off two match points, Murray eventually wrapped up the historic victory. The victory over Djokovic means he ends the year with a 24-match winning streak.
The Serb made light work of Japan's Kei Nishikori in his semi-final on Saturday and has nearly spent three hours lesser on the court than Murray in the ongoing tournament.
He also played a marathon in the last group stage match against Kei Nishikori, which extended for three hours and 20 minutes on Tuesday. "It is something I never expected".
Tennis world No 1 Andy Murray.
To get to the tiebreakers, Djokovic saved three break points in the first set.
Normally so steady with his groundstrokes, Djokovic found himself missing easy shots time after time, finishing the match with a whopping 30 unforced errors and only 13 winners.
For the first time in the history of the ATP World Tour, the two best men's #Tennis players faced off with the world No.1 ranking on the line. I've played so much tennis the last few months and long matches this week.
Djokovic added: "Andy is clearly number one of the world, he's the best player".
"I didn't do much from my side".
Murray appeared to lose concentration temporarily in the second set, with a number of distractions from the raucous London crowd who were cheering for him, as the chair umpire called for silence in the arena.
"I was solid enough when I needed to be", Murray said, perhaps understating his accomplishment. "I'm pretty sure I'm going to feel like crap tomorrow", said Raonic who is still without a career win against a resident world number one. He is the best player.
"It has [been] a fantastic year with some great highlights, especially in the first six months". But the majors are what gets me working hard and what really, really motivates me.
"It really could have gone either way", said Djokovic, who completed a career grand slam by winning the French Open this year. "This is maybe one of the biggest matches we will ever play, so let's enjoy it".
The defeat concludes a second half to the season during which the 29-year-old has failed to win a tournament - a period which Murray has taken full advantage of.