Barclays ATP World Tour Finals - Day Six [Getty Images]

LONDON, ENGLAND - NOVEMBER 09: Roger Federer of Switzerland celebrates match point to win his men's singles match against Juan Martin Del Potro of Argentina during day six of the Barclays ATP World Tour Finals at O2 Arena on November 9, 2013 in London, England. (Photo by Clive Brunskill/Getty Images)

Getty Images Sport Clive Brunskill