Jeff Hopkins' Victory side, typically among the main contenders for silverware, are locked in a scrap for a top-six berth and realistically needed to finish their season with three wins to make finals.
Holly Furphy's goal in the 57th minute proved enough for Victory to tick off the first of those three wins, while officially ending 10th-placed Western Sydney's own finals hopes.
Fifth-placed Victory (25 points) trail Melbourne City (30), Adelaide United (29), Wellington (28) and Canberra (27), with Perth (22), Central Coast (22) and Brisbane (20) all having games in hand.
Victory took the lead at the Home of the Matildas on Saturday when Kennedy White was released by Chelsea Blissett and should have buried the goal but shot straight at Shamiran Khamis.
The Wanderers goalkeeper's save spilled straight to Furphy, who nailed a beautiful left-foot volley.
"The main message was just 'treat this like a finals game,'" Furphy told Paramount Plus of Hopkins' half-time speech.
"At this point, we do need to win every game and put away those points, so it was really (important) to have that hunger and desire to get that ball in the back of the net, and we did that."
Earlier at Sky Stadium, Phoenix young gun Manaia Elliott nodded home the opener in the 10th minute, with Emma Pijnenburg adding a second six minutes later.
Wellington star recruit Macey Fraser, who has missed most of the season for personal reasons, came on at halftime to make her first appearance since rejoining the Phoenix.Makala Woods buried Brisbane when she finished from close range in the 72nd minute.
Roar skipper and Matildas veteran Tameka Yallop came off the bench in the 82nd minute, marking her return from a serious hamstring injury that ruined her Asian Cup hopes.
Phoenix goalkeeper Victoria Esson pulled off an extraordinary point-blank reflex save to maintain the clean sheet in the 84th minute, leaping and sticking out one hand to hook the ball to safety.
City and Canberra will close out the round on Sunday.
