MASON, OH - AUGUST 16: Grigor Dimitrov of Bulgaria returns a shot to Novak Djokovic of Serbia during the Western & Southern Open at Lindner Family Tennis Center on August 16, 2018 in Mason, Ohio. (Photo by Matthew Stockman/Getty Images)
MASON, OH - AUGUST 16: Grigor Dimitrov of Bulgaria returns a shot to Novak Djokovic of Serbia during the Western & Southern Open at Lindner Family Tennis Center on August 16, 2018 in Mason, Ohio. (Photo by Matthew Stockman/Getty Images)