ATP World Tour Finals: Novak Djokovic beats Roger Federer in opening round

Novak Djokovic started his ATP World Tour Finals defence with a second win over Roger Federer in the space of four days.

Djokovic beat the Swiss veteren en route to the Paris Masters title last week and again proved too strong despite the crowd siding with his opponent at the O2 Arena in London.

The Serb, bidding for a fourth straight title after tournament, closed out a 6-4 6-7 6-2 victory in two hours and 22 minutes.

Both players now have a day off before resuming their Group B campaigns on Thursday, Djokovic against Juan Martin del Potro and Federer taking on Richard Gasquet.

Serve dominated until sixth seed Federer – appearing at the season-ending tournament for the 12th year in a row – carved out the first break point in the ninth game and only just missed with a forehand down the line.

Second seed Djokovic held for a 5-4 lead and then moved 15-40 up as Federer served to stay in the set.

The Swiss saved the first set point but misfired with a forehand on the second to hand Djokovic the opening set.

The second set saw Federer twice move a break up and he served for the set at 5-4 ahead, holding set point at 40-30.

But another wayward forehand – one of his 45 unforced errors – allowed Djokovic to escape and force a tie-break, only for Federer to dominate it 7-2 and take the match in a decider.

Djokovic produced an immediate response, breaking in the opening game of the final set and again for a 4-1 lead before serving out the win.