An Australian Open courtesy car waits outside the Grand Hyatt hotel in central Melbourne, Australia, Thursday, Feb. 4, 2021.
All competition at six Australian Open tuneup events scheduled for Thursday was called off after a worker at one of the tournaments' Melbourne quarantine hotels tested positive for COVID-19.
The Australian Open is scheduled to begin Monday.
Williams won her last major title at the 2017 Australian Open, when she was pregnant with her daughter, Olympia.
On the bottom half of the draw, defending Australian Open champion Sofia Kenin rallied from a set and a break down to fend off Jessica Pegula 5-7, 7-5, 6-2.