It was an action-packed affair for the Walkinshaw Andretti United star, who led the early part of the race after out-pacing Shane van Gisbergen and Jamie Whincup on the opening lap.
He lost that lead on a Lap 7 restart, before finding himself in an epic battle for second place with rival Cam Waters across the second stint.
Famous for making contact a number of times while Tickford teammates, the pair were at it again with two laps to go as Mostert tapped Waters into a spin at the first corner.
He slowed to redress the situation, which brought Andre Heimgartner and Jamie Whincup into the battle for third place.
Heimgartner initially climbed through to third, only for Mostert to cart him wide at turn one next time around, Whincup passing them both to score the final spot on the podium.
Speaking post-race Mostert said he apologised to Heimgartner as he lost a position, but also felt he’d been blocked into Turn 1.
He added that he felt like he deserved a trophy off the back to two spectacular battles for a spot on the podium across the race.
“[Heimgartner] kind of blocked me into [Turn] 1 as I had a run off the last corner,” Mostert told Fox Sports.
“I don’t know what he expected me to do, but I never really want someone, by passing them, to lose a position, which he did to Jamie.
“WAU pay me to have cracking moves, have a go and try and get a result, and I fought hard twice today with Cam and Andre.
“I had a ripper race, I probably deserved a trophy. As a team we had a much better car than yesterday. We have one more race, hopefully we can come from further back and get a trophy.”
Heimgartner, meanwhile, said he was annoyed to miss out on the podium after being run wide by Mostert.
“I’m pretty disappointed that we finished fifth in that one when we were coming third and the car was pretty speedy,” said the Kelly Grove Racing driver.
“It’s a podium that got away. I went as deep as I could unto Turn 1 and I knew Chaz, coming up the inside, was going to be pushing it to get around the corner. Unfortunately I just got pushed wide onto the grass and that gave up the spot to Whincup as well.
“Pretty disappointing, but it’s not entirely his fault, just one of those racing things. I’m more annoyed that we weren’t able to get that trophy.
“It is what it is. There was a little bit of red mist when it happened, I felt like punching him off the track.
“In hindsight I probably could have blocked a bit more but I didn’t think he’d go up the inside given it was so dirty and wet. It’s just one of those things.”