The ATP Tour finals is a men's indoor hard-court tennis tournament played at the O2 Arena in London, England, from 13 to 20 November 2016. It is the season-ending event for the best singles players and doubles teams on the 2016 ATP World Tour. The 2016 edition will be the 47th in the history of the competition. The top eight players in the ATP rankings qualify for the singles event and are split into two groups. Players compete in a round-robin format with the top two players in each group progressing to the semi-finals. The doubles competition uses the same format.Serbia's Novak Djokovic is the reigning singles champion, while Jean-Julien Rojer and Horia Tecau are the current doubles champions.