Mark Milligan's penalty on the stroke of half-time moved Kevin Muscat's men three points of clear of Sydney FC, who alongside Wellington Phoenix remain only a mathematical shot at the premiership in the final round.
Roar fielded several young players in their starting XI as the reigning champions suffered a second straight defeat to Victory in a matter of days.
"It's been a long time [since Victory's last trophy] but it's still not mathematically done," Melbourne midfielder Leigh Broxham said.
"It's sweet at the moment and we'll take it one game at a time."
Victory host Central Coast Mariners in the final regular-season game next Sunday, by which time they may have already been confirmed as premiers for the first time since 2009.
In Saturday's other action, Mark Bridge celebrated his 200th A-League game with a goal, an assist and a win as Western Sydney Wanderers beat a 10-man Adelaide United 2-1 at Pirtek Stadium.
The match turned on Nigel Boogaard's red card just after the hour mark as Tomi Juric's ensuing penalty and Bridge's clinical finish gave the home side a hard-earned win, having fallen 1-0 behind in the first half.
The result was extra significant as the Wanderers move off the bottom of the table ahead of next week's final round
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