Nick Percat admitted he "hated every second" at former team Walkinshaw Andretti United after breaking through for his first Supercars win in four years.
The now-Matt Stone Racing driver outpaced championship leaders Broc Feeney and Will Brown to claim the chequered flag at Albert Park on Sunday.
Starting fourth on the grid to pole-sitter and former teammate Chaz Mostert (Walkinshaw Andretti United) and hot favourite Matt Payne (Grove Racing), Percat was able to snare the lead on lap three when Mostert and Payne collided.
The one-time Bathurst 1000 winner proved his mettle and held on throughout the 14-lap sprint to claim his fifth career win and first with Matt Stone Racing after leaving Mostert and team in the off-season.
Brown was just 0.38 seconds slower than Percat, while Feeney trailed behind 0.99 seconds to come third.
Percat was so desperate to claim the drought-breaking victory that he emptied his fuel tank, requiring PremiAir Nulon Racing driver Tim Slade to push him back to the pits.
"It's unbelievable," Percat said.
"I wanted to quit and now round two, we've won a race.
"The last 18 months I hated every second of that mob (Walkinshaw Andretti United) so, honestly, the moment I walked into MSR, I knew this is where I needed to be ... it's a bit surreal."
Asked what pushed him to continue his career, Percat credited the support of the young racers at his karting team JND Racing.
"It got pretty low," Percat said.
"I was trying to avoid the track - get here as late as possible, leave here as quick as possible.
"The JND kart team - those kids are all nine to 15, dream of being in a Supercar and they pretty much said to me, 'We need you to keep racing, we love watching you, you can get the right car' and that gave me a lot of motivation.
"When I met Matt and the team, I understood what they were doing here and I was like, 'I've got to be in this car'.
"It's pretty cool when you have young karters, dream race karters, motivating you so much when it gets a bit tough.
"They give you a reality check. There's 25 seats available and they love watching me come last or first."
Payne, desperate for redemption after crashing out on Saturday afternoon, blitzed Mostert from the starting gun and looked certain to storm home victorious.
Instead, Payne was made to settle for a finish in 14th after being hit twice.
The young New Zealander was first sent through the grass at turn 10 on lap three when the Walkinshaw Andretti United driver, locking his left-hand front, clipped the back of his Ford Mustang, before a hit by Bryce Fullwood sent him spiralling again in lap four.
Mostert and Fullwood were both slapped with a five-second penalty, with Mostert dropping from fourth to fifth and Fullwood finishing 20th as a result.
RACE SIX RESULTS:
1. Nick Percat (Matt Stone Racing)
2. Will Brown (Triple Eight)
3. Broc Feeney (Triple Eight)
4. Tom Randle (Tickford Racing)
5. Chaz Mostert (Walkinshaw Andretti United)
CHAMPIONSHIP STANDINGS:
1. Will Brown (Triple Eight) 575 points
2. Broc Feeney (Triple Eight) 558
3. Chaz Mostert (Walkinshaw Andretti United) 478
4. Nick Percat (Matt Stone Racing) 405
5. David Reynolds (Team 18) 358
