Shane van Gisbergen made the best of a frantic end to a tricky opening practice session for drivers at the Repco SuperSprint at The Bend.
The 30-minute session was held in overcast conditions, with sprinkles of rain having some impact on running, but never proving enough to require the wet tyres.
The key times all came in the final minutes, with the top of the timesheet changing rapidly as many ran a second set of slicks.
Scott McLaughlin led the way with five minutes to go, before being knocked off by Tickford teammates Lee Holdsworth and Cameron Waters.
Walkinshaw Andretti United rookie Bryce Fullwood then appeared to trump the whole field with the chequered flag flying, going fastest on 1:48.2581s.
Van Gisbergen though shot from 20th to P1 moments later, saving a slide out of the final corner to go fastest by 0.1368s.
Fullwood had been among the six drivers to complete the morning's earlier rookie session, but did not expect to be so competitive among the full field.
“I was pretty surprised to be honest, but we’ve been developing our car over the last few events,” he said.
“I feel like on green tyre, as a quali car when I get everything together, our package isn’t bad. Our race car is where we’ve got to focus.
“We’ve tried some different things from Townsville his weekend and it’s rolled out pretty good, I’m pretty happy with it.”
Waters and Holdsworth ended up third and fourth, 0.4229s and 0.5044s adrift of the Kiwi respectively.
Andre Heimgartner and Anton De Pasquale were among other late improvers in fifth and sixth, demoting McLaughlin to seventh.
Jack Le Brocq, Nick Percat and Garry Jacobson rounded out the top 10, with Mark Winterbottom – who ran as high as P2 in the final three minutes – 11th.
Winterbottom described driving in the changing conditions as a "weird feeling".
“It starts spitting rain, you give the wiper one sweep and hope there’s not too much coming back on [to the windscreen],” he said.
“It’s a weird feeling because it really feels like it’s going to have a big downpour but it just didn’t come.
“When it’s like that the track is quite quick, but it’s a fine line between a couple of drops and 8 to 10mm, or whatever the forecast is.
“The rain is coming, it just depends on what session.”
The sprinkles of rain made for some hairy moments throughout, the biggest of which was a high-speed spin for Pye midway through.
Pye rejoined with his Team 18 Commodore undamaged and ended up 18th on the timesheet, two places ahead of title contender Jamie Whincup.
A second practice session will take place prior to ARMOR ALL Qualifying, with more rain forecast for throughout the day.