Tags: Tennis Tournament, Tournament.
The 2011 ATP World Tour Finals (also known as the 2011 Barclays ATP World Tour Finals for sponsorship reasons) was a tennis tournament that was played at the O2 Arena in London United Kingdom between 20 and 27 November 2011. The defending champion in singles was world no. 4 Roger Federer while the defending champions in doubles were Daniel Nestor and Nenad Zimonjić. However they did not defend their title together as they separated after the 2010 event.