Federer beats Sock in ATP Finals opener
Roger Federer got his ATP World Tour Finals campaign off to a winning start with a straight sets win over Jack Sock.
The 19-time Grand Slam winner came through 6-4, 7-6 in their round-robin tie.
Federer says it was a tricky opening match:
In the other meeting in the Boris Becker Group, Alexander Zverev came from behind to beat Marin Cilic 4-6, 6-3, 6-4.
Meanwhile, Rafael Nadal is in action Monday as he faces David Goffin in the Pete Sampras Group, with Dominic Thiem taking on Grigor Dimitrov.