The state reported 1503 new COVID-19 cases on Wednesday from 92,262 test results - the most processed in a 24-hour window since the pandemic began in early 2020.
The overwhelming demand for testing has forced at least 14 testing sites across the city to shut as of 9.45am, after reaching capacity.
They span from the east at Golfers Drive in Chadstone, southeast at Peninsula Health in Frankston and north at Heidelberg Repatriation Hospital.
In Melbourne, the Bourke Street walk-in and Montague Street drive-through both remain shut.
Albert Park's drive-through was also inundated, immediately suspending testing after opening, for a third straight day.
It has since reopened to incoming traffic.
Acting Premier James Merlino, who has attributed the surging demand to people needing a test to travel interstate for Christmas, urged people to be patient and says that for most sites the wait was 40 minutes on average.
Mr Merlino had been slated to stand in for Premier Daniel Andrews at Wednesday's national cabinet meeting, when Australia's leaders will discuss indoor mask requirements and vaccine boosters amid the spread of the Omicron variant.
But the premier will now briefly return from leave for the meeting before Mr Merlino resumes his role as acting premier.
Victoria will join other states to call for the COVID-19 vaccine booster interval to be further reduced from five months to three or four months at the virtual meeting.
More than 17,000 Victorians were vaccinated in state-run hubs on Tuesday, as the national booster program gathers momentum.
Victoria's active case numbers remain relatively stable at 13,888, as do hospitalisations intensive care figures.
A total of 394 COVID-related patients are in hospital, including 70 who are actively infected with the virus and in intensive care, with 41 on ventilators.
The seven-day hospitalisation average has risen marginally to 391.
A further six Victorians have also died with COVID-19, taking the state's toll across the pandemic to 1466.