Five best shots as Federer fights back against Cilic
ATP Finals
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."