Jennifer Brady returns a shot during the women's singles third round match between Jennifer Brady of the United States and Petra Kvitova of the Czech Republic at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Jennifer Brady lost 1-2. (Xinhua/Mahmoud Khaled)

　　Jennifer Brady serves during the women's singles third round match between Jennifer Brady of the United States and Petra Kvitova of the Czech Republic at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Jennifer Brady lost 1-2. (Xinhua/Mahmoud Khaled)

　　Jennifer Brady returns a shot during the women's singles third round match between Jennifer Brady of the United States and Petra Kvitova of the Czech Republic at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Jennifer Brady lost 1-2. (Xinhua/Mahmoud Khaled)

　　Petra Kvitova returns a shot during the women's singles third round match between Jennifer Brady of the United States and Petra Kvitova of the Czech Republic at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Petra Kvitova won 2-1. (Xinhua/Mahmoud Khaled)

　　Petra Kvitova serves during the women's singles third round match between Jennifer Brady of the United States and Petra Kvitova of the Czech Republic at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Petra Kvitova won 2-1. (Xinhua/Mahmoud Khaled)

　　Simona Halep returns a shot during the women's singles third round match between Simona Halep of Romania and Lesia Tsurenko of Ukraine at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Simona Halep won 2-0. (Xinhua/Mahmoud Khaled)

　　Simona Halep returns a shot during the women's singles third round match between Simona Halep of Romania and Lesia Tsurenko of Ukraine at Dubai Duty Free Tennis WTA Championships 2019 in Dubai, the United Arab Emirates, Feb. 20, 2019. Simona Halep won 2-0. (Xinhua/Mahmoud Khaled)