Serena Williams of the United States celebrates victory after the third round of women's singles match against Ekaterina Alexandrova of Russia at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Ekaterina Alexandrova of Russia returns the ball against Serena Williams of the United States during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Ekaterina Alexandrova of Russia returns the ball against Serena Williams of the United States during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Serena Williams of the United States returns the ball against Ekaterina Alexandrova of Russia during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Ekaterina Alexandrova of Russia returns the ball against Serena Williams of the United States during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Serena Williams of the United States returns the ball against Ekaterina Alexandrova of Russia during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)

Serena Williams of the United States returns the ball against Ekaterina Alexandrova of Russia during the third round of women's singles match at the 2019 Rogers Cup in Toronto, Canada, Aug. 8, 2019. Serena Williams of the United States won 2-0. (Xinhua/Zou Zheng)