Novak Djokovic produced another scintillating performance to beat Stanislas Wawrinka at the ATP World Tour Finals.

The world No.1 recovered from losing the first two games to win 12 of the next 13 in a 6-3, 6-0 win. He has not lost at the O2 Arena since 2011 and is unbeaten in 29 matches indoors.

Djokovic remains top of Group A with his final round-robin match against Tomas Berdych to come.

The Serb will guarantee the year-end No.1 ranking with another win on Friday, and it is hard to see who can stop him claiming a hat-trick of ATP World Tour Finals titles on Sunday.

"I swung through my shots and he made a lot of errors," said Djokovic. "He wasn't close to his best and I succeeded very well with what I wanted to do."

Earlier, Tomas Berdych rebounded from an opening defeat to revive his hopes at the ATP World Tour Finals by demolishing Croatia's Marin Cilic 6-3, 6-1.

Berdych, who lost to Stanislas Wawrinka on Monday, will now go into his final match against Djokovic still hopeful of a semi-final place, but Cilic, who has managed to win only six games in two matches, would need a bizarre sequence of results to reach the weekend.