LONDON, ENGLAND - NOVEMBER 14: Novak Djokovic of Serbia practices before the start of of the Nitto ATP World Tour Finals at The O2 Arena on November 14, 2020 in London, England. (Photo by TPN/Getty Images)
LONDON, ENGLAND - NOVEMBER 14: Novak Djokovic of Serbia practices before the start of of the Nitto ATP World Tour Finals at The O2 Arena on November 14, 2020 in London, England. (Photo by TPN/Getty Images)