Overnight rain made for a wet start to Saturday's action in South Australia, conditions improving across the first half-hour session without the track full drying out.
That meant there was a flurry of late times, Winterbottom the best of them with a 1m50.494s on his final run.
That was good enough to put the Team 18 driver three-hundredths clear of series leader Shane van Gisbergen, who was a consistent front-runner throughout the session.
Winner of the last race Chaz Mostert was third fastest while James Courtney was best of the Fords in fourth. That was despite the Tickford driver prompting a short stoppage after beaching his Mustang at Turn 6.
Anton De Pasquale, Cam Waters and Will Davison were next as Will Brown, Scott Pye and Tim Slade rounded out the Top 10.
| Cla | # | Driver | Car | Time | Gap | Interval |
|---|---|---|---|---|---|---|
| 1 | 18 |  Mark Winterbottom | Holden Commodore ZB | 1'50.494 | ||
| 2 | 97 |  Shane van Gisbergen | Holden Commodore ZB | 1'50.533 | 0.039 | 0.039 |
| 3 | 25 | Chaz Mostert | Holden Commodore ZB | 1'50.602 | 0.108 | 0.069 |
| 4 | 44 | James Courtney | Ford Mustang GT | 1'50.607 | 0.113 | 0.005 |
| 5 | 11 | Anton De Pasquale | Ford Mustang GT | 1'50.826 | 0.332 | 0.219 |
| 6 | 6 | Cameron Waters | Ford Mustang GT | 1'50.855 | 0.361 | 0.029 |
| 7 | 17 | Will Davison | Ford Mustang GT | 1'50.927 | 0.432 | 0.071 |
| 8 | 9 | Will Brown | Holden Commodore ZB | 1'51.065 | 0.571 | 0.138 |
| 9 | 20 | Scott Pye | Holden Commodore ZB | 1'51.112 | 0.618 | 0.046 |
| 10 | 3 | Tim Slade | Ford Mustang GT | 1'51.139 | 0.645 | 0.027 |
| 11 | 8 | Nick Percat | Holden Commodore ZB | 1'51.230 | 0.736 | 0.091 |
| 12 | 5 | Jack Le Brocq | Ford Mustang GT | 1'51.353 | 0.858 | 0.122 |
| 13 | 88 | Jamie Whincup | Holden Commodore ZB | 1'51.509 | 1.015 | 0.156 |
| 14 | 96 | Macauley Jones | Holden Commodore ZB | 1'51.585 | 1.090 | 0.075 |
| 15 | 55 | Thomas Randle | Ford Mustang GT | 1'51.733 | 1.238 | 0.148 |
| 16 | 99 | Brodie Kostecki | Holden Commodore ZB | 1'51.872 | 1.377 | 0.138 |
| 17 | 14 | Todd Hazelwood | Holden Commodore ZB | 1'51.898 | 1.404 | 0.026 |
| 18 | 4 | Jack Smith | Holden Commodore ZB | 1'52.056 | 1.561 | 0.157 |
| 19 | 7 | Andre Heimgartner | Ford Mustang GT | 1'52.255 | 1.761 | 0.199 |
| 20 | 19 | Fabian Coulthard | Holden Commodore ZB | 1'52.440 | 1.945 | 0.184 |
| 21 | 35 | Zane Goddard | Holden Commodore ZB | 1'52.519 | 2.025 | 0.079 |
| 22 | 2 | Bryce Fullwood | Holden Commodore ZB | 1'53.063 | 2.569 | 0.544 |
| 23 | 34 | Jake Kostecki | Holden Commodore ZB | 1'53.648 | 3.153 | 0.584 |
| 24 | 27 | Kurt Kostecki | Holden Commodore ZB | 1'53.725 | 3.231 | 0.077 |
| 25 | 22 | Garry Jacobson | Holden Commodore ZB | 1'54.178 | 3.683 | 0.452 |
| 26 | 26 | David Reynolds | Ford Mustang GT | 1'57.759 | 7.265 | 3.581 |
| View full results | ||||||
