Victory bounced back from their Derby capitulation with a clinical win against the defending champions in Melbourne.
The hosts, who led at half-time through Jimmy Jeggo's goal, saw Zac Anderson equalise for the Mariners, before he gave away a penalty which James Troisi converted. Substitute Kosta Barbarouses added another goal in injury time to seal three much-needed points for Kevin Muscat's side.
The win lifts Victory above the Mariners and Adelaide and into third on the table, with seven points separating them from seventh place ahead of the rest of the weekend's action.
Having suffered five defeats from their last six A-League matches, the Mariners will be looking over their shoulder during the final five rounds of the campaign as they seek to prolong their title defence.
A combination of international duty, injury and suspension forced four changes to the Victory starting XI and three from the Mariners' last outing, and the upheaval on both sides was evident in a cagey, disjointed start to the game.
It took until the 11th minute for the first real sight of goal to arrive. Even then it was only by accident, Leigh Broxham nearly diverting Kim Seung-Yong's corner into his own net, with the woodwork and Mitchell Duke's inability to control the rebound sparing the Victory.
After a considerable lull the hosts finally mustered a shot on target, Guilherme Finkler shooting straight at Liam Reddy from long range in the 29th minute.
The Mariners came within inches of opening the scoring two minutes later, when Nick Fitzgerald flashed a header just wide of goal from Duke's delivery.
The next opportunity fell to the hosts less than 60 seconds later, and, despite having previously laboured without reward, they seized it without hesitation.
Finkler, positioned inside the penalty area, did well to cushion down Connor Pain's pass from out wide before turning and laying it off to Jeggo, who took a touch and beat his man, firing through a crowded penalty area and into the far corner of the net.
A livelier start to the second half produced several openings. Fitzgerald tested Lawrence Thomas and Duke got in behind the Victory defence, while at the other end Pain broke free inside the area but opted to try and find a team-mate when shooting seemed a better option.
It was the Mariners who forced the next breakthrough and they had a Victory goalkeeping error to thank for it, something that has become a familiar sight in recent weeks.
Thomas, promoted last week in place of the inconsistent Nathan Coe, failed to clear a routine delivery from a set-piece, missing the ball completely and allowing Anderson to stab home the equaliser.
The goal-scorer turned unfortunate villain of the piece for the visitors in the 76th minute, handling an Archie Thompson shot inside the area and conceding a penalty which Troisi slammed home off the underside of the crossbar.
Barbarouses made absolutely certain of the spoils late on when he finished off a Victory counter-attack by tucking the ball beyond a helpless Reddy from close range.