Mao-Xin Gong Pictures
BEIJING, CHINA - OCTOBER 06: Mao-Xin Gong (L)of China and Michael Venus of New Zealand return a ball against Novak Djokovic of Serbia and Djordje Djokovic of Serbia during the day four of the 2015 China Open at the China National Tennis Center on October 6, 2015 in Beijing, China. (Photo by Emmanuel Wong/Getty Images)