Jamie Whincup topped a frantic wet-dry final practice session at Barbagallo Raceway, while Scott McLaughlin will have to go the long way in qualifying after missing an automatic Q2 spot.
Morning showers meant damp conditions to start the 20-minute session, with times hanging around 61-second mark early on as most of the field circulated on wet tyres.
Six minutes in Tim Blanchard dropped into the 60-second bracket on a slick tyre, sparking a mass change to the dry weather rubber.
The first half-representative time came right at the midway point of the session, Nick Percat going top with a 57.916s, before improving to a 56.912s two minutes later.
His Brad Jones Racing teammate Tim Slade was next to have a stint on top thanks to a 56.855s, although he was quickly displaced by rookie Anton De Pasquale's 56.833s with just under seven minutes to go.
With five minutes to go McLaughlin made his move, going from the bottom of the field to a top with a 56.619s.
The next change came at the beginning of the 'Happy Hour', Rick Kelly first to take on a last-gasp green tyre run with a 56.222s with three minutes to go.
Shane van Gisbergen then went from outside the Top 20 to top spot with a 55.331s on his green run, before being replaced by teammate Whincup – who was dead last – with a 55.268s.
That proved to be the hammer blow, Whincup ending the session 0.04s clear of Chaz Mostert.
Will Davison improved on his final run to slot into third, which dropped van Gisbergen back to fourth.
BJR pair Nick Percat and Tim Slade ended up fifth and sixth with late improvements, with David Reynolds seventh.
Kelly, who had been top with three minutes to go, was shuffled all the way to the back of the field due to the flurry of late times, before jumping back to eighth on his final run.
Andre Heimgartner made it two Nissans in the Top 10 with the ninth quickest time, while James Golding grabbed the final automatic Q2 spot.
That meant McLaughlin missed out on Q2, yesterday's polesitter and race winner finishing 12th after initially being bumped out of the Top 10 by Golding's time.
"We didn't run greens, I don't know whether other people did or not," said McLaughlin. "Maybe we got caught out by that. I had a fair bit of push then, too.
"I'm confident we can come through on the three runs, but we just missed the boat there. You always want to be in Q2, but we didn't run the green set, so at least we've got a set of tyres up our sleeve. It's okay. We've just got one extra qualifying session we've got to get through."
McLaughlin isn't the only big name that will have to come through Q1 today. Mark Winterbottom, who finished second yesterday, was just 19th, and didn't even have tyre condition to blame.
"The weather didn't really help," he said. "I just didn't get the lap. The tyres were good, I just didn't get the lap. I dropped a wheel on the wet line on the exit and dropped a heap of time. Yeah, tough session. It's mixed up sort of grid now, so getting through the Top 6 will be tough."
The Walkinshaw Andretti United duo were even worse off, James Courtney and Scott Pye finishing up 25th and 26th respectively.
"To be honest I thought it was okay with the way the tyre was, what we had," explained Courtney. "It was good in the wet, we were up there. But then at the end there when everyone put on their better sets, their better sets were obviously better than ours.
"Would have been nice to be in that 10 so we didn't have to do that first part of quali, but the sun is out, it's a new day..."
|1||1||Jamie Whincup||Holden Commodore ZB||55.2686|
|2||55||Chaz Mostert||Ford Falcon FG X||55.3115||0.0429|
|3||400||Will Davison||Ford Falcon FG X||55.3226||0.0540|
|4||97||Shane van Gisbergen||Holden Commodore ZB||55.3315||0.0629|
|5||8||Nick Percat||Holden Commodore ZB||55.3442||0.0756|
|6||14||Tim Slade||Holden Commodore ZB||55.3464||0.0778|
|7||9||David Reynolds||Holden Commodore ZB||55.4220||0.1534|
|8||15||Rick Kelly||Nissan Altima||55.5771||0.3085|
|9||7||Andre Heimgartner||Nissan Altima||55.5772||0.3086|
|10||34||James Golding||Holden Commodore ZB||55.6000||0.3314|
|11||23||Michael Caruso||Nissan Altima||55.6525||0.3839|
|12||17||Scott McLaughlin||Ford Falcon FG X||55.6849||0.4163|
|13||21||Tim Blanchard||Holden Commodore ZB||55.7012||0.4326|
|14||18||Lee Holdsworth||Holden Commodore ZB||55.7468||0.4782|
|15||99||Anton de Pasquale||Holden Commodore ZB||55.7701||0.5015|
|16||56||Richie Stanaway||Ford Falcon FG X||55.7736||0.5050|
|17||888||Craig Lowndes||Holden Commodore ZB||55.7991||0.5305|
|18||35||Todd Hazelwood||Ford Falcon FG X||55.8020||0.5334|
|19||5||Mark Winterbottom||Ford Falcon FG X||55.8580||0.5894|
|20||6||Cameron Waters||Ford Falcon FG X||55.8600||0.5914|
|21||12||Fabian Coulthard||Ford Falcon FG X||55.9270||0.6584|
|22||33||Garth Tander||Holden Commodore ZB||55.9612||0.6926|
|23||78||Simona de Silvestro||Nissan Altima||56.0865||0.8179|
|24||19||Jack Le Brocq||Holden Commodore ZB||56.1077||0.8391|
|25||25||James Courtney||Holden Commodore ZB||56.1610||0.8924|
|26||2||Scott Pye||Holden Commodore ZB||56.4883||1.2197|