Novak Djokovico made a quick work of John Isner to win his opening match at the ATP Finals.

The world No.1  defeated the 6ft 10 big serving American in what was a comfortable 6-4 6-3 win at the O2 Arena.

Following his injury spell, the Serbian is back in full throttle, having entered Wimbledon in July ranked No.21 in the world, Djokovic is once again top of the tree and was presented with the year-end world No.1 trophy on Sunday after lifting his fourth SW19 crown and triumphing at the US Open, as well as claiming titles in Cincinnati and Shanghai.

Djokovic is a clear favorite to win this title as Roger Federer was terribly out of sorts in his loss to Kei Nishikori on Sunday.

Winning would move the Serb level with the Swiss master’s six ATP Finals titles.

Isner, at 33 now the oldest debutant at the Finals boomed down his usual missiles, but Djokovic had break points in his first two service games before making one count in his third.