Novak Djokovic is safely into the last four of the ATP World Tour Finals.

The Serbian tennis star beat Tomas Berdych 6-2 6-2 to make it three straight sets wins in the group stage.

It confirms his status as the year end World Number One and will face Japan's Kei Nishikori in the semi-finals.

The final qualifier will be decided tonight when Stan Wawrinka meets Marin Cilic.

The Swiss just needs to win a set to confirm his place in the semis.

His countryman Roger Federer sealed his place in the last four last night when he crushed Andy Murray in straight sets.