There was drama before the second race of the weekend even started, initially thanks to delays from the crash-affected Formula 3 qualifying.
That meant the Supercars race went from a 15-lap duration to a time certain finished at 3:33pm local time plus one lap.
As the delayed start neared there was a light sprinkle of rain around the Albert Park precinct, the race declared wet for a second time in as many days.
At the same time there was an issue with the starting lights that meant the Australian flag had to be used to get the race underway.
When the flag did finally wave it was Will Brown that got the jump from the outside of the front row to grab the lead from polesitter Shane van Gisbergen.
Kostecki briefly got in front of van Gisbergen as well, although the Kiwi was able to re-establish second by midway through the first lap.
It was at that point the safety car was called, David Reynolds left beached at Turn 1 after a tussle with Cam Waters and Mark Winterbottom.
As the race was neutralised Nick Percat's miserable start to the year continued as his Mustang's V8 engine caught fire.
He limped back to the pits where the flames were extinguished, although the car was left badly scorched.
The Lap 4 restart led to some wild racing at the front, van Gisbergen making a play for the lead that saw him run wide at Turn 5 and dropped him back to fifth in the order.
Kostecki came out of the madness in front while James Courtney slid down to the inside of Brown to take second place.
Interest then turned to the mandatory stops, the wet declaration meaning those that started on super softs only needed to take on two new tyres.
From Lap 5 onwards the field filtered through the pits, Kostecki, Courtney and van Gisbergen among the last to do so right as the safety car was called for a second time on Lap 7.
This time the culprit was Jack Le Brocq who sideswiped the wall on the way through the fast Turn 8 complex.
Kostecki, Courtney and van Gisbergen managed to get out ahead of the field to reclaim the top three spots, the race then ending under safety car as Kostecki scored his first Supercars win.
Feeney ended up fourth ahead of Chaz Mostert and Anton De Pasquale, while Brown was shuffled back to seventh amid the stops due to starting on hards and needing four tyres.
Bryce Fullwood finished eighth from Thomas Randle and James Golding.
Mostert continues to lead the series, although the gap to Kostecki is now just 11 points.
The Melbourne SuperSprint continues with two back-to-back qualifying sessions starting at 9:05am and then a third race at 5:30pm.
