
Novak Djokovic of Serbia reacts during the quarterfinal match of men's singles against Juan Martin Del Potro of Argentina at the Italian Open tennis tournament in Rome, Italy, May 20, 2017. Novak Djokovic won 2-0. (Xinhua/Jin Yu)

Novak Djokovic of Serbia reacts during the quarterfinal match of men's singles against Juan Martin Del Potro of Argentina at the Italian Open tennis tournament in Rome, Italy, May 20, 2017. Novak Djokovic won 2-0. (Xinhua/Jin Yu)