Melina Ayres' brilliant hat-trick and some magic from goalkeeper Casey Dumont have lifted Melbourne Victory to a thrilling A-League Women's semi-final win against their city rivals via a penalty shootout.

Victory looked home and hosed leading 3-1 with 12 minutes of regulation time to play but had to go and win the game again after Melbourne City's Hannah Wilkinson sent the game to extra time with a dramatic 97th-minute equaliser.

With the scores remaining locked through the additional period, it went down to spot-kicks to decide the winner.

Dumont, who had stopped a penalty in normal time, not only scored the opening goal in the shootout but saved from City's Kate Bowen, with a miss from Wilkinson letting Victory claim the win with a 4-1 advantage from the spot.

She said her sky-high confidence had allowed her to lead Victory to the famous win.

"You've got to have the confidence, if you don't believe in yourself it's not gonna happen," she told Paramount.

"I knew where I was going and picked the spot out and went, and then it was the same with having a stop on the penalty as well, I just pick a side and go.

"The girls asked (if i could shoot first) and I was like 'yeah, no worries, I'll do it'. We practised in the week as well, that's always the first person who sets the momentum.

"I'll happily do that for the team."

The two-time reigning champions will face the loser of Sunday's semi-final between Sydney FC and Western United in a preliminary final next weekend for the right to face the winner in the decider at Western Sydney's CommBank Stadium.

Ayres is just the second player in ALW history to score a hat-trick in a finals game, joining Matildas superstar Sam Kerr who netted a treble against Victory for Perth in the 2019 semi-final.

Victory had one foot in the preliminary final when Ayres completed her hat-trick in the 72nd minute, chesting down a cross and sliding the ball past City keeper Melissa Barbieri for 3-1.

She had put her side into the lead five minutes earlier with an absolute peach, curling the ball past Barbieri from just inside the box.

But City showed their fight, with Rhianna Pollicina hammering home a bobbling ball to make it 3-2 and set up a grandstand finish.

As the game headed into its seventh minute of added time, Wilkinson drifted in to get on the end of a bungled clearance and head the ball past Dumont to level the scores and force the additional half-hour.

Pollicina had grabbed the lead for City on 40 minutes, and while it was against the run of play, her brilliant interplay with Holly McNamara certainly warranted a goal.

But Victory were level early in the second half, Beattie Goad crunched in the box by Naomi Chinnama with Ayres tucking away the subsequent penalty for the first of her treble.

Dumont said Victory's never-say-die attitude had been needed to answer the multiple challenges thrown at them by City.

"You saw the celebrations earlier, that is the culture," she said.

"No matter what, even if we have a bad training session, the girls get behind each other at the end to be like 'no, we're not walking off this pitch angry or upset'.

"This season alone has spoken wonders on that because next week, we've got to switch back on and go again."