Battle for world No.1 goes down to year's final game

Fitness and fatigue will determine who wins the final match of the season - Andy Murray or Novak Djokovic.

Britain's Andy Murray returns the ball against Milos Raonic of Canada at the ATP World Tour Finals at the O2 Arena in London. Picture: WILL OLIVER

TENNIS: Fitness and fatigue will determine who wins the final match of the season - Andy Murray or Novak Djokovic - and who finishes No.1 in the world.

They will face off in the final of the ATP World Tour Finals in London on Monday morning (4am AEST), the first time the battle for the top spot has been fought in the final match of the season.

Murray took three hours and 38 minutes to beat Milos Raonic 5-7 7-6 (7-5) 7-6 (11-9) to reach his first season-ending final.

Djokovic coasted past Japan's Kei Nishikori 6-1 6-1 in just one hour and six minutes in his semi.

"I'm tired. I've played so much tennis over the last few months,” Murray said.

"I'll give it my best effort - the best of what I have.”

The win was Murray's second lengthy encounter in four days, breaking the tournament record of three hours and 20 minutes he took to beat Nishikori in the round-robin stage on Wednesday.

The 17,000 spectators at the O2 Arena screamed at every twist and turn before Murray finally won.

"It was an amazing atmosphere,” Murray said.

"The longer the match went on, the louder the crowd got. This is what we play for. Matches like this and arenas like this. This is one of hardest matches I've played indoors.”

Originally published as Battle for world No.1 goes down to year's final game