Defending champion Madison Keys has been knocked out of the Australian Open by Jessica Pegula in an all-American fourth-round match.

Naomi Osaka has withdrawn from the Australian Open before her third-round match against Maddison Inglis.

Jannik Sinner made a dramatic comeback at the Australian Open, overcoming cramps and getting benefit from the tournament's extreme heat policy to beat Eliot Spizzirri.

The safety protocols for COVID-19 have been a touchy subject at the Australian Open.

Spain's Rafael Nadal reacts during his first round match against Serbia's Laslo Djere at the Australian Open tennis championship in Melbourne, Australia, Tuesday, Feb. 9, 2021. Daniil Medvedev extended his winning streak to 15 matches with a 6-2, 6-2, 6-4 win over Vasek Pospisil and seventh-seeded Andrey Rublev beat Yannick Hanfmann 6-3, 6-3, 6-4. 9 Matteo Berrettini defeated Kevin Anderson, a two-time finalist at majors, 7-6 (9), 7-5, 6-3. Barty lost to Sofia Kenin in the Australian Open semifinals last year and then skipped the U.S. Open and her title defense at the French Open because she stayed in Australia during the COVID-19 pandemic. AdTwo-time Australian Open quarterfinalist Tennys Sandgren also went through the hard lockdown.