Guillermo Garcia-Lopez of Spain returns a shot during the men's singles first round match against Stan Wawrinka of Switzerland at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland reacts during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Guillermo Garcia-Lopez of Spain serves during the men's singles first round match against Stan Wawrinka of Switzerland at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Guillermo Garcia-Lopez of Spain waves to the spectators during the men's singles first round match against Stan Wawrinka of Switzerland at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Guillermo Garcia-Lopez of Spain celebrates after winning the men's singles first round match against Stan Wawrinka of Switzerland at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland serves during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland returns a shot during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland returns a shot during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland returns a shot during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)

Stan Wawrinka of Switzerland returns a shot during the men's singles first round match against Guillermo Garcia-Lopez of Spain at the French Open Tennis Tournament 2018 in Paris, France, on May 28, 2018. Stan Wawrinka lost 2-3. (Xinhua/Luo Huanhuan)