Grigor Dimitrov signs autographs for fans after winning the Men's Singles Final during day eight of the NITTO ATP World Tour Finals at the O2 Arena, London. (Photo by Adam Davy/PA Images via Getty Images)
Grigor Dimitrov signs autographs for fans after winning the Men's Singles Final during day eight of the NITTO ATP World Tour Finals at the O2 Arena, London. (Photo by Adam Davy/PA Images via Getty Images)