|Venue: The 02 Arena, London Dates: 12-19 November|
|Coverage: Watch live on BBC Two, Red Button, BBC Sport website and mobile app, listen on BBC Radio 5 live sports extra and follow text updates online.|
Roger Federer fought back to beat Marin Cilic in three sets and head into the semi-finals with an unbeaten record from the ATP Finals group stage.
Federer, who had already secured a place in the last four after two wins, completed the round-robin stage with a 6-7 (5-7) 6-4 6-1 victory.
Germany’s Alexander Zverev takes on American Jack Sock in the final Boris Becker Group match at 20:00 GMT.
The winner will join Federer and Grigor Dimitrov in the semis.
Saturday’s semi-final line-up will be completed by the winner of the Pete Sampras Group match between Dominic Thiem and David Goffin at 14:00 on Friday.
“Knowing I was qualified on Tuesday evening – it’s kind of weird to be already through to the semis, but of course it gives me a great idea how I want to prepare for Saturday,” said Federer.
“One more last weekend, one more push before the vacation and then preparation for the next season.”
‘I was in trouble’ – Federer
Federer and Cilic met for the first time since a one-sided Wimbledon final, which saw the Swiss win a 19th Grand Slam title as Cilic struggled with a blister on his foot.
The Croat put up sterner resistance for the better part of two sets at the O2 Arena, before Federer ran away with the contest, winning eight of the last nine games.
Federer could have made shorter work of it had he converted one of three break points in the opening game but Cilic clung on, and a beautiful backhand volley at 5-5 in the tie-break saw the fifth seed edge ahead.
A break point early in the second set offered real opportunity for Cilic but Federer stood firm at the net, and once he finally broke serve to take the second set there was only one winner.
The Swiss six-time champion raced through the final set to reach the semi-finals for the 14th time in 15 appearances at the ATP season finale.
“I think it was a tough match, a lot of chances maybe in the first set,” said Federer.
“I think Marin served well and was a bit better in the breaker. I was in trouble a set and a break point down in the second set, so I’m happy I found a way out of it and in the end I played really well.”
|Follow tennis with the BBC|
|Alerts: Tennis news sent to your phone|
|My Sport: Sign up to follow tennis news|