Xu Xin (L) of China shakes hands with Timo Boll of Germany after their men's singles quarterfinal match at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Xu Xin won 4-0. (Xinhua/Wang Dongzhen)

Xu Xin of China reacts during the men's singles quarterfinal match against Timo Boll of Germany at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Xu Xin won 4-0. (Xinhua/Wang Dongzhen)

Timo Boll of Germany competes during the men's singles quarterfinal match against Xu Xin of China at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Timo Boll lost 0-4. (Xinhua/Wang Dongzhen)

Timo Boll of Germany returns the ball during the men's singles quarterfinal match against Xu Xin of China at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Timo Boll lost 0-4. (Xinhua/Wang Dongzhen)

Xu Xin of China returns the ball during the men's singles quarterfinal match against Timo Boll of Germany at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Xu Xin won 4-0. (Xinhua/Wang Dongzhen)

Xu Xin of China reacts during the men's singles quarterfinal match against Timo Boll of Germany at ITTF World Tour Platinum China Open in Shenzhen, south China's Guangdong Province on June 1, 2019. Xu Xin won 4-0. (Xinhua/Wang Dongzhen)