Xu Jiayu of China competes during the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Athletes start during the men's 50m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Athletes start during the men's 50m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Ji Xinjie (1st L), Xu Jiayu (2nd L), Sun Yang (2nd R) and Wang Shun of China pose for photos after the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Sun Yang of China competes during the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Sun Yang (3rd R), Ji Xinjie (2nd R), Wang Shun (1st R) and Xu Jiayu (Bottom) of China celebrate after the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Sun Yang of China competes during the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Zhang Yufei of China reacts after the women's 50m butterfly preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Zhang Yufei of China reacts after the women's 50m butterfly preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Li Zhuhao(R) of China and Joseph Schooling of Singapore check the screen after the men's 100m butterfly preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Xu Jiayu (L) and Sun Yang of China talk with each other after the men's 4x200m freestyle relay preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Zhang Yufei of China gets ready before the women's 50m butterfly preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Li Zhuhao of China competes during the men's 100m butterfly preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Yu Hexin(1st L) of China is seen before the men's 50m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Wang Jianjiahe of China competes during the women's 800m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Li Bingjie of China competes during the women's 800m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Peng Xuwei of China competes during the women's 200m backstroke preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Wang Jianjiahe of China competes during the women's 800m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Yu Hexin(front) of China starts during the men's 50m freestyle preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Liu Yaxin of China starts during the women's 200m backstroke preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)

Liu Yaxin of China competes during the women's 200m backstroke preliminary at the Gwangju 2019 FINA World Championships in Gwangju, South Korea, July 26, 2019. (Xinhua/Tao Xiyi)