Spain's Rafael Nadal reacts during men's singles semifinal of Tennis against Argentina's Juan Martin del Potro at the 2016 Rio Olympic Games in Rio de Janeiro, Brazil, on Aug. 13, 2016. Juan Martin del Potro won 2-1. (Xinhua/Yue Yuewei)
Spain's Rafael Nadal reacts during men's singles semifinal of Tennis against Argentina's Juan Martin del Potro at the 2016 Rio Olympic Games in Rio de Janeiro, Brazil, on Aug. 13, 2016. Juan Martin del Potro won 2-1. (Xinhua/Yue Yuewei)