Novak Djokovic began his bid for a record fourth straight end-of-season title with victory over Japan’s Kei Nishikori at the ATP World Tour Finals. The Serb won 6-1 6-1 to claim his 15th consecutive win at London’s O2 Arena, a run stretching back to 2011. The world number one needed just 65 minutes to see off eighth seed Nishikori, and ended the afternoon with a trophy in his hands as he was confirmed as the 2015 world number one.

Djokovic, 28, won the Australian Open, Wimbledon and US Open, and went within one match of the calendar Grand Slam, losing to Stan Wawrinka in the French Open final. Nishikori, 25, did not serve well enough to give Djokovic any trouble and was broken five times as the Serb extended his latest winning streak to 23 matches. All the players wore black ribbons on their shirts as a mark of respect to the victims of Friday’s deadly attacks in Paris.

Did You Know???

Djokovic, a Serbian professional tennis player, is currently ranked world No. 1 in men’s singles tennis by the Association of Tennis Professionals (ATP).

Djokovic holds the best match winning rate at (83.33%) on hard courts and he is the only player in the Open Era to win the first three masters in a year (2015: Indian Wells, Miami Open and Monte Carlo).

In August 2015, Djokovic was appointed as the UNICEF Gooddwill Ambassador.