With captain Tom Abercrombie having been sidelined through injury, that likely leaves two members of the playing staff involved in the outbreak.
And Stuff reported that there were expectations the number of positive cases could grow following further testing, throwing into doubt the season-opening game against South East Melbourne Phoenix next Saturday.
The Breakers' final warm-up game against the Illawarra Hawks - which had been scheduled for Thursday - had already been cancelled, with the touring party being forced to self-isolate in their Melbourne apartments since last Sunday night.
The team returning to the practice court today was a positive sign but any further positive tests would leave the Breakers in danger of being seriously under-manned for the start of the new season.
All players and staff associated with the Breakers in Australia are double-vaccinated.
"Our team has followed best practices but, unfortunately, a number of individuals have experienced symptoms," Breakers owner Matt Walsh said after the initial outbreak had been announced.
"We will continue to follow the advice of medical professionals and the NBL and look forward to being back on the court soon."