Rafael Nadal of Spain returns a shot during the men's singles semifinal match against Juan Martin Del Potro of Argentina at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Juan Martin Del Potro of Argentina returns a shot during the men's singles semifinal match against Rafael Nadal of Spain at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Juan Martin Del Potro of Argentina serves during the men's singles semifinal match against Rafael Nadal of Spain at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Rafael Nadal of Spain returns a shot during the men's singles semifinal match against Juan Martin Del Potro of Argentina at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Juan Martin Del Potro of Argentina returns a shot during the men's singles semifinal match against Rafael Nadal of Spain at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Rafael Nadal of Spain returns a shot during the men's singles semifinal match against Juan Martin Del Potro of Argentina at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Luo Huanhuan)

Juan Martin Del Potro of Argentina returns a shot during the men's singles semifinal match against Rafael Nadal of Spain at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Rafael Nadal (R) of Spain greets Juan Martin Del Potro of Argentina after the men's singles semifinal match at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Juan Martin Del Potro of Argentina returns a shot during the men's singles semifinal match against Rafael Nadal of Spain at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)

Rafael Nadal of Spain reacts during the men's singles semifinal match against Juan Martin Del Potro of Argentina at the French Open Tennis Tournament 2018 in Paris, France on June 8, 2018. Rafael Nadal won 3-0. (Xinhua/Chen Yichen)