London: Novak Djokovic was at his imperious best as he sealed the year-end world number one spot and advanced to the semi-finals of the ATP Tour Finals with a 6-2, 6-2 thrashing of Tomas Berdych on Friday.


Novak Djokovic 

Djokovic finishes on top of the rankings for the third time in four seasons and is only the seventh player to hold first place at the end of the calender year on at least three occasions. The Serb's third successive victory at the prestigious season-ending event at London's O2 Arena ensured he won Group A and will face Japan's Kei Nishikori in Saturday's semi-finals.