LONDON, ENGLAND - NOVEMBER 17: Roger Federer of Switzerland shakes hands with against Alexander Zverev of Germany during Day Seven of the Nitto ATP Finals at The O2 Arena on November 17, 2018 in London, England. (Photo by Fred Lee/Getty Images)
LONDON, ENGLAND - NOVEMBER 17: Roger Federer of Switzerland shakes hands with against Alexander Zverev of Germany during Day Seven of the Nitto ATP Finals at The O2 Arena on November 17, 2018 in London, England. (Photo by Fred Lee/Getty Images)