When is Roger Federer vs Alexander Zverev? Start time at the ATP World Tour Finals

Federer opening his campaign with a routine win over Jack Sock, although the American put up more of a fight than the 6-4, 7-6 scoreline suggests.

Having only qualified by winning the Paris Masters less than two weeks ago, Sock was broken just once in the entire match and saved five break points in the process.

And Federer admitted he was still feeling his way into the tournament, a “really, really difficult” thing to do against a top-10 player.

Zverev meanwhile narrowly escaped an early defeat to Marin Cilic, coming back from 3-1 down in the deciding set to seal 6-4, 3-6, 6-4 victory on Sunday night.

But the German did not seem overawed by the occasion, despite the fact it was his first ever ATP World Tour Finals match.

Federer will be playing on this stage for the 66th time when they meet tonight in the biggest match of the day at the O2 Arena.

They will be preceded by a doubles clash between Pierre-Hugues Herbert & Nicolas Mahut vs Ryan Harrison & Michael Venus.

Those four men will get underway at 6pm while Federer and Zverev are due on court “not before 8pm”.

However, so far this week the majority of night matches have got underway at about 8.20pm and Federer and Zverev should be expected around the same time.

ATP World Tour Finals schedule Day 3

12pm: Kontinen/Peers vs Rojer/Tecau

Not before 2pm: Cilic vs Sock

6pm: Herbert/Mahut vs Harrison/Venus

Not before 8pm: Federer vs Zverev