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

LONDON, ENGLAND - NOVEMBER 15: Kei Nishikori of Japan shakes hands with Novak Djokovic of Serbia after the singles semi-final match on day seven of the Barclays ATP World Tour Finals at O2 Arena on November 15, 2014 in London, England. (Photo by Julian Finney/Getty Images)

Getty Images Sport Julian Finney