The Victoria state health department said two players and a third person associated with the tournament — a woman in her 20s, and two men in their 30s — had returned positive results.
The Australian Open, already delayed by three weeks to February 8, has been rocked by the detection of Covid-19 among the more than 1,000 players and staff who flew into the country on charter flights.
A total of nine people have tested positive while in quarantine ahead of the event in Melbourne, but two cases were deemed to be historical infections on Tuesday.
Positive cases on three charter flights have left 72 players confined to their hotel rooms, rather than being allowed out to train like the other competitors.
But health officials said none of the 72 had yet been cleared to train as a result of the two cases being reclassified as non-infectious.
“This does not change broader assessment of the player group in hotel quarantine,” a statement said.
Some players have complained that the possibility of a hard lockdown was not explained before they travelled to Australia, and have raised concerns about their fitness for lead-up events beginning January 31.
Many have turned their hotel rooms into makeshift gyms and resorted to hitting tennis balls off hotel walls.