Home Serena Williams of the United States reacts in her fourth round match against Simona Halep of Romania during day eight of the 2019 Australian Open at Melbourne Park on January 21, 2019 in Melbourne, Australia.<br>(Photo by Quinn Rooney/Getty Images) Serena Williams of the United States reacts in her fourth round match against Simona Halep of Romania during day eight of the 2019 Australian Open at Melbourne Park on January 21, 2019 in Melbourne, Australia.<br>(Photo by Quinn Rooney/Getty Images)

Serena Williams of the United States reacts in her fourth round match against Simona Halep of Romania during day eight of the 2019 Australian Open at Melbourne Park on January 21, 2019 in Melbourne, Australia.
(Photo by Quinn Rooney/Getty Images)

Serena Williams of the United States reacts in her fourth round match against Simona Halep of Romania during day eight of the 2019 Australian Open at Melbourne Park on January 21, 2019 in Melbourne, Australia.<br>(Photo by Quinn Rooney/Getty Images)
Naomi Osaka of Japan hits a backhand in her fourth round match against Anastasija Sevastova of Latvia during day eight of the 2019 Australian Open at Melbourne Park on January 21, 2019 in Melbourne, Australia.<br>(Photo by Jonathan DiMaggio/Getty Images)