Andy Murray and Novak Djokovic set up a Sunday shootout for both the ATP finals title and the year-end No. 1 ranking.

The world's top two players had contrasting wins in the semifinals at O2 Arena on Saturday, with Murray surviving a match point to beat Milos Raonic 5-7, 7-6 (5), 7-6 (9) in 3 hours, 38 minutes, the longest ever three-setter in the ATP finals.

Djokovic needed just 66 minutes to dispatch Kei Nishikori 6-1, 6-1.

Murray arrived at the tournament simply needing to do better than Djokovic to finish the year at No. 1, a position he has held since winning the Paris Masters two weeks ago.

Now, that means winning the final.

"This has never happened in the history of tennis," Djokovic said of the winner-takes-all match on Sunday. "I'm privileged to be part of the history. This is one of the biggest matches we will ever play against each other."

Djokovic might just be in better shape after overwhelming Nishikori, who held his serve only once all match.

"I pretty much executed everything I tactically planned to do," Djokovic said.

"My level had been going in the right direction. I'm very glad I get to experience this feeling on the court. Now it's coming up to the last match of the year, the match everybody anticipated."

After squandering chances while serving for the match twice in the final set, Murray converted on his fourth match point during the tiebreaker to finally come through.

"It was unbelievably tough," Murray said. "I had to fight very, very hard. Being broken twice serving for the match was frustrating. It was one of the harder matches I've played indoors. They are never this long."

Murray had won all six of his meetings with Raonic this year, including a straight-sets victory in the Wimbledon final.

Murray just needs one last push at the end of a stunning second half to 2016, when he has won Wimbledon and the Olympics before topping the rankings for the first time.

"I'm tired," Murray said. "I've played so much tennis the last few months. I'll just give my best effort tomorrow. It's going to be tough, obviously, but I'll give my best shot."