Summary
Novak Djokovic beats Kei Nishikori 6-1 6-1
Djokovic trying to reclaim world number one ranking
Djokovic won all three group matches; Nishikori won one, lost two
Live from London's O2 Arena
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Praise for Murraypublished at 20:33 Greenwich Mean Time 19 November 2016
Murray takes the tough routepublished at 20:32 Greenwich Mean Time 19 November 2016
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End of twitter postSo you might have noticed earlier that there was match on court that lasted three hours and 38 minutes. That's right Andy Murray somehow, somehow overcame one heck of a fight from world number four Milos Raonic.
He battled to a 5-7 7-6 (7-5) 7-6 (11-9) win over the Canadian to book his place in Sunday's final.
If Nishikori wins tonight then Murray will be number one at the start of 2017, if Djoko is his opponent then he'll have to beat him in the final.
Pile on those carbs Andy.
'The more Novak is challenged the better he is'published at 20:31 Greenwich Mean Time 19 November 2016
Novak Djokovic's coach Boris Becker speaking to Sky Sports: "Novak had been challenged earlier on in the tournament. The more he's challenged the better he is. Kei is one of the fastest and most talented players. Novak has to pick his moment when he wants to accelerate."
What's left in the Nishikori tank?published at 20:30 Greenwich Mean Time 19 November 2016
Djokovic v Nishikori
Image source, Rex FeaturesThe players are pretty much running on empty after another energy sucker of a season.
Nishikori who competed against Murray for three hours and 20 minutes in midweek looked a bit tired in the three setter against Marin Cilic yesterday, which he lost.
The Japanese player said after the defeat: "I hope I can play better tomorrow. I will try to think tonight or tomorrow what I have to do to beat Djoko. I mean, I’m obviously not playing bad."
Djoko has a 10-2 record against the 26-year-old - this is a good time for Kei to make it 10-3.
Murray & Soares lose but are handed a trophypublished at 20:27 Greenwich Mean Time 19 November 2016
Image source, Getty ImagesAndy Murray's brother Jamie doesn't have to reach the men's doubles final to hold on to his status as one half of the best men's pairing in the world.
Actually, he isn't in Sunday's final after both he and Bruno Soares were beaten by South Africa's Raven Klaasen and the USA's Rajeev Ram 6-1 6-4.
But J Muzza and Soares have just received a big silver trophy for ending the year as world number one.
Congrats!
Djoko wins toss & will servepublished at 20:27 Greenwich Mean Time 19 November 2016
Djokovic v Nishikori
Image source, Getty ImagesNishikori is to receive first. We are moments away.
Players are on courtpublished at 20:26 Greenwich Mean Time 19 November 2016
Djokovic v Nishikori
Apparently Hugh Grant's in the crowd - case of Three Matches and a ...I can't think of a substitute word for 'Funeral'.
The players are out on the court. The toss is coming up.
'No! I want the number one spot'published at 20:18 Greenwich Mean Time 19 November 2016
Djokovic v Nishikori
Image source, Rex FeaturesJust as soon as your heart rate has returned to a normal resting level we have another semi-final which is predicted to be as pulsating (and possibly lengthy).
Here's the situation: Novak Djokovic must win to have a chance of taking back the world number one ranking from Andy Murray.
So there's a lot, I mean a lot at stake.
Stay here for live text coverage and we have live commentary on BBC Radio 5 live sports extra.