Rafael Nadal celebrates after winning the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Rafael Nadal celebrates after winning the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Diego Schwartzman hits a return during the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Rafael Nadal (R, front) shakes hands with Diego Schwartzman after winning the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Rafael Nadal celebrates after winning the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Rafael Nadal celebrates after winning the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Diego Schwartzman reacts during the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)

Diego Schwartzman hits a return during the men's singles quarterfinal match between Rafael Nadal of Spain and Diego Schwartzman of Argentina at the 2019 US Open in New York, the United States, Sept. 4, 2019. (Xinhua/Li Muzi)