LONDON, ENGLAND - NOVEMBER 12: Novak Djokovic of Serbia poses with Roger Federer of Switzerland as he holds the trophy following their men's singles final match against Roger Federer of Switzerland during day eight of the ATP World Tour Finals at O2 Arena on November 12, 2012 in London, England.  (Photo By Tommy Hindley/Professional Sport/Popperfoto via Getty Images/Getty Images)