Jamie Whincup emerged fastest from an opening Symmons Plains practice session that saw the Red Bull Holdens and Shell V-Power Fords duke it out at the top.
Shell V-Power twins Fabian Coulthard and Scott McLaughlin sat atop the order for much of the 45 minutes before a late spurt from Whincup turned the tables.
Whincup went to the top with five minutes remaining, eventually stopping the clocks with a 50.945s best, eclipsing his own practice record from 2014.
McLaughlin improved to within 0.14s of the pace with a late effort of his own, splitting the Red Bull entries of Whincup and Shane van Gisbergen.
Mobil 1 HSV Racing driver Scott Pye demoted Coulthard down to fifth as the Kiwi failed to improve on his final run.
Coulthard had earlier engaged in an on-track battle with Van Gisbergen, denting the rear bumper of the Holden as they made contact out of Turn 4.
Van Gisbergen spent much of the session on the harder of the two compound tyres but appeared in no mood to let his super soft shod rival through, defending into the hairpin.
“It was good fun,” smiled Coulthard when asked of the practice ‘race’. “Shane races fair and hard and that’s what it’s going to be like all year I think.”
Chaz Mostert survived a wild slide at the exit of the final turn to end up sixth ahead of Will Davison, Lee Holdsworth, Mark Winterbottom and Tim Slade.
Nick Percat was 11th despite causing the only red flag when he locked up and slid into the gravel at Turn 4.
“I’m battling with a bit of front locking,” he said after climbing from his Holden that was rebuilt after brake failure caused a heavy crash at Albert Park two weeks ago.
“The brakes are working exceptionally well this weekend compared to the last time I drove it!”
James Courtney was down in 21st but, having not run the super soft, was encouraged by his team’s package.
“I flat-spotted a tyre at the GP in our super soft set, so I had to run the harder compound all that session,” he explained.
“We’re trying to hunt that balance, but the car was quite good before everyone started bolting super softs on and went quite a bit quicker.
“Scotty (Pye) ran a set on his car and it went quite well.”
Craig Lowndes was just 22nd after power steering issues limited him to just 20 laps.
“We want to make sure we get out this afternoon and have a good strong run, so we opted to stop early, get it fixed and obviously get out this afternoon,” he said.
“It’s a bit of a shame. The car is actually working very well, we’d made some good progress and just put on some new tyres to do a simulation of where we could have been.”
A second 40 minute session is scheduled for 3pm local time this afternoon.