LONDON (Reuters) - Serbia's Novak Djokovic clinched his place in the semi-finals of the ATP World Tour Finals when he won the first set of his final round-robin match against Tomas Berdych 6-3 on Thursday.
The world number one required only one set to take the runners-up spot in his group behind unbeaten group winner Roger Federer who earlier beat Kei Nishikori.
He will face Rafael Nadal in the semi-final on Saturday.
Djokovic, holder at the London year-ender, was well beaten by Federer on Tuesday but bounced back with two service breaks in the opening set against Berdych to take it comfortably.
The Czech's only chance of qualifying for the semis was to beat Djokovic in straight sets, although with two wins in 22 matches against the Serb it was a tall order.
(Reporting by Martyn Herman; editin by Ken Ferris)