
Novak Djokovic of Serbia returns the ball during the final match of men's singles against Alexander Zverev of Germany at the Italian Open tennis tournament in Rome, Italy, May 21, 2017. Novak Djokovic lost 0-2. (Xinhua/Jin Yu)

Novak Djokovic of Serbia returns the ball during the final match of men's singles against Alexander Zverev of Germany at the Italian Open tennis tournament in Rome, Italy, May 21, 2017. Novak Djokovic lost 0-2. (Xinhua/Jin Yu)