United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula hits a forehand to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina hits a backhand to Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Ukraine's Elina Svitolina, left, plays Kazakhstan's Yulia Putintseva during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

France's Kristina Mladenovic opens her arms after a shot to United States' Jessica Pegula during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

Karolina Pliskova of the Czech Republic serves to compatriot Karolina Muchova during their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Feb. 13, 2021.(AP Photo/Andy Brownbill)

Kazakhstan's Yulia Putintseva hits a forehand to Ukraine's Elina Svitolina during their third round match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. (AP Photo/Hamish Blair)

United States' Jessica Pegula serves to France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)

United States' Jessica Pegula, top, plays France's Kristina Mladenovic during their match at the Australian Open tennis championships in Melbourne, Australia, Saturday, Feb. 13, 2021. The Australian Open continues but without crowds after the Victoria state government imposed a five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel. (AP Photo/Hamish Blair)