Federer opens up with straightforward win over Sock

With Andy Murray and Novak Djokovic both missing through injury, Federer and Rafael Nadal are the stand-out attractions at the O2 Arena, where the game's favourite rivalry is due to replay in the knock-out stages.

But first they must each navigate their way through their respective groups and Federer made a smooth start, beating American Sock 6-4 7-6 (7/4) in an hour and a half.

The last time the Swiss won this tournament was in 2011, a year before the start of his four-year grand slam drought, which had many concluding his best days were behind him.

But, now 36, and making his 15th appearance here, Federer is looking to add to the Wimbledon and Australian Open titles he has already won this season, and against Sock he seemed ominously fresh.

He hit 28 winners without offering Sock a single break point and while the 19-time major champion was not as clinical in the second set as he might have been, victory was never really in doubt.

Sock, making his first appearance here and yet to go further than the fourth round at a grand slam, took a while to find his rhythm and Federer pounced with a break in the very first game.

A punching backhand winner was followed by a dipping forehand to Sock's feet before another singing backhand gave Federer the early initiative.

Sock gradually settled his nerves as the set wore on and he had a sniff of a break back at 3-2 but a Federer ace and then a brilliantly picked up half-volley averted the danger.

Sock held serve for 5-3 in the strangest of fashions after he turned away and ducked his head to allow his opponent the entire court to finish off a short forehand. Instead, Federer lashed it into the net before both players shared a sheepish smile.

Federer was less generous moments later as an ace secured the set but Sock maintained momentum in the second frame, which was tighter than the first.

Sock had to fight hard to keep it close, defending five Federer break points, including two at 4-4, to force a tie-break. A disgruntled Federer pulled 4-2 clear but again Sock came back, with a successful challenge to make it 4-4.

Sock blinked at the crucial moment, however, as a double fault put Federer back in charge and he converted his first match point when a Sock forehand dropped long.