Covers on...published at 22:09 Greenwich Mean Time 14 November 2016
Thanks again for joining us today.
Come back on Tuesday for some more action from the ATP Finals in London.
Summary
Andy Murray beats Marin Cilic 6-3 6-2
Murray's first victory since becoming world number one
Nishikori beat Wawrinka earlier in same group
Group John McEnroe at London's O2 Arena
Covers on...published at 22:09 Greenwich Mean Time 14 November 2016
Coming up...published at 22:06 Greenwich Mean Time 14 November 2016
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End of twitter postWe will have full coverage of that match. Nishikori played brilliantly against Wawrinka earlier on Monday - it promises to be a heck of a contest.
That's quite a large tennis ball...published at 21:59 Greenwich Mean Time 14 November 2016
Media caption, ATP World Tour Finals: Five great shots as Novak Djokovic beats Dominic Thiem
In case you missed it Novak Djokovic - now world number two (sorry Novak) - won his opening ATP Finals match on Sunday.
After a bit of a blip in the first set Djoko fought back to defeat Dominic Thiem 6-7 (10-12) 6-0 6-2.
Catch up with some of the action above.
Nishikori overwhelms underwhelming Wawrinkapublished at 21:54 Greenwich Mean Time 14 November 2016
Media caption, ATP World Tour Finals 2016: Five best shots as Kei Nishikori beats Stan Wawrinka
Earlier today, world number three Stan Wawrinka was pretty awful in his opening group match against world number five Kei Nishikori.
The US Open champion lost 6-2 6-3. Trounced really. He didn't bother talking to the straight-off-court TV team. I don't blame him.
'I played one of my best matches here'published at 21:53 Greenwich Mean Time 14 November 2016
Murray 6-3 6-2 Cilic
Image source, Getty ImagesAndy Murray speaking to Sky Sports: "It's a great atmosphere and I think I played one of my best matches here. I'm going to keep working hard to give people moments like this.
"I have confidence from winning matches and I was a little bit more solid when I had opportunities."
Postpublished at 21:52 Greenwich Mean Time 14 November 2016
Miles Maclagan
Former British Davis Cup player on Radio 5 live sports extra
Image source, ReutersThat was a very strong performance from Andy Murray. He'll look to improve his serve a little bit but mentally more than anything else was the difference. He has this warrior mentality.
'Murray will be near his best by the latter stages'published at 21:52 Greenwich Mean Time 14 November 2016
Murray 6-3 6-2 Cilic
Piers Newbery
BBC Sport in LondonIt was as much about the occasion as the performance, and Murray did his bit by getting off the mark with a win as world number one.
Eleven winners to 19 errors tells its own story but the Scot improved markedly in the second set, and looked somewhere near his best by the latter stages.
Next up will be Kei Nishikori on Wednesday, and another win should be enough to get Murray to the weekend. Calculators at the ready.
'Tough to start against the best in the world'published at 21:51 Greenwich Mean Time 14 November 2016
Murray 6-3 6-2 Cilic
Marin Cilic speaking to Sky Sports: "I think I played quite well. I was unfortunate in the first set on a few points. Overall I played well and enjoyed the atmosphere. It was a big pleasure for me.
"It was tough to start straight away against the best in the world.
On the colourful shorts: "The shorts are something different and a few colours doesn't hurt."
A few colours Marin???!!
Postpublished at 21:47 Greenwich Mean Time 14 November 2016
David Law
Radio 5 live sports extra commentator
Image source, AFPThis crowd is treating Murray like a rock star. I'm not sure Cilic can believe the scoreline - he's played quite well - but Murray has been fabulous.
Game, set and matchpublished at 21:47 Greenwich Mean Time 14 November 2016
Murray 6-3 6-2 Cilic
Murray must be incredibly frustrating to play against when he starts to read everything you throw at him.
Cilic at the net thinks he's won the point but Murray passes him and then makes an error after misjudging Murray's angled backhand volley at the net.
The scores move to 40-0 before taking the first match point as Cilic's return finds the middle of the net.
That's it. Murray wins his 20th successive match. Pretty incredible.
Postpublished at 21:43 Greenwich Mean Time 14 November 2016
Miles Maclagan
Former British Davis Cup player on Radio 5 live sports extraMurray is now putting daylight between himself and the world number seven. He's not played great tennis but he's getting the job done.
Murray breaks againpublished at 21:43 Greenwich Mean Time 14 November 2016
*Murray 6-3 5-2 Cilic
Image source, Rex FeaturesHe's in the zone.
Murray stands just inside the baseline after his initial return on Cilic's serve and hits a forehand to make it 0-15 before Cilic falters once more.
The Croat finds the net rather than the other side of the court and it's break point again.
Murray takes it with a winner rather than an error - an excellent fly-swat of a forehand return.
He just needs to hold now.
Postpublished at 21:38 Greenwich Mean Time 14 November 2016
Miles Maclagan
Former British Davis Cup player on Radio 5 live sports extra
Image source, AFPThere have been some sticky moments but Murray is like a boxer who draws your swings and punches and then hits you with jabs from the left and then the right.
Murray likes his boxing - it's a very Floyd Mayweather-style performance.
Postpublished at 21:37 Greenwich Mean Time 14 November 2016
Murray 6-3 4-2 Cilic*
Image source, ReutersMurray again changes the pace with a delicate backhand from back of the court which Cilic again fails to read - 15-0.
An error by the Scot and a Cilic winner follows, but Murray counters with a brilliant first serve - 30-30.
Cilic then makes two unforced errors from the back of the court - long returns - as Murray holds.
He's two games away from winning the first match. Dogged.
Postpublished at 21:31 Greenwich Mean Time 14 November 2016
David Law
Radio 5 live sports extra commentatorWhen Lendl is around you always feel that Murray goes after the forehand more. He just seems to not rally as much but try to put the ball away.
Murray breakspublished at 21:31 Greenwich Mean Time 14 November 2016
*Murray 6-3 3-2 Cilic
Image source, Rex FeaturesHas the Scot got first wind?
He wins the opening point with a great return down the line before forcing an error from Cilic, who slaps his forehand into the net - it's 15-30.
Cilic then makes another error after an intriguing rally which saw Murray again change the pace.
Two break points. Murray makes another challenge - he gets it wrong again, as Cilic's serve in called in.
But he converts the remaining break point by changing the trajectory of his return which wrongfoots the Croat.
Postpublished at 21:25 Greenwich Mean Time 14 November 2016
Murray 6-3 2-2 Cilic*
Murray's first serve percentage before this game in this set was 44% and points won on it is at 50%. That's "real sad" to quote a president elect.
Nevertheless, he wins this service game to love. The first time he's managed that in this contest.
About time.
Postpublished at 21:21 Greenwich Mean Time 14 November 2016
Miles Maclagan
Former British Davis Cup player on Radio 5 live sports extraThe players are not giving an inch and this is a real contest.
Postpublished at 21:21 Greenwich Mean Time 14 November 2016
*Murray 6-3 1-2 Cilic
Image source, ReutersThis is Cilic's best service game so far. One serve and volley winner and then one from the back of the court.
It's 40-15. This is a breeze for the Croat.
Ahh...
Murray punishes Cilic for weak execution at the net before punishing his opponent again with a great passing shot. Deuce.
But two big serves gets Cilic out of that spot of bother.
The Croat only won 62% of points on his first serve in the opening set - that's up to 75% in the second.
Postpublished at 21:16 Greenwich Mean Time 14 November 2016
David Law
Radio 5 live sports extra commentatorMarin Cilic is such a nice bloke but right now he's a bit frightening. He's stalking the baseline. These are two big players going toe to toe.