World number 61 Jessica Pegula will play her friend Jennifer Brady in the quarter-finals at Melbourne Park after shocking Elina Svitolina.
Ash Barty was too hot to handle in a straight-sets win over last year's US Open quarter-finalist Shelby Rogers in Melbourne on Monday.
Serena Williams' coach Patrick Mouratoglou discussed the 23-time grand slam champion's improved movement.
Serena Williams and Simona Halep will meet in the quarter-finals, while Naomi Osaka also advanced at Melbourne Park.
A painful-looking fall did not cause Serena Williams undue concern against Aryna Sabalenka as she continues to multi-task in Melbourne.
In her biggest test so far at Melbourne Park this year, Serena Williams overcame seventh seed Aryna Sabalenka in the round of 16.
Naomi Osaka was all smiles after progressing to the quarter-finals at Melbourne Park on Sunday.
Craig Tiley allayed fears over the Australian Open after Michail Pervolarakis tested positive for COVID-19 on his arrival in South Africa.
Karolina Pliskova took out her frustrations during a third-round defeat, but Ash Barty was able to reach week two in Melbourne.
World number one Ash Barty admitted it was "very strange" without spectators after triumphing at Melbourne Park on Saturday.