The second half-hour of running kicked off with Walkinshaw Andretti United leading the way, initially thanks to Mostert, who was then usurped by Ryan Wood after 12 minutes.

There was some more shuffling at the midway point of the session, full-time debutant Jayden Ojeda enjoying a brief stint on top before Matt Payne lowered the benchmark to a 1m08.987s.

The session then came alive in the closing minutes as focus switched to pre-qualifying performance runs.

Initially it was Cam Hill that went fastest, before Mostert jumped to the top on one lap, and he widened his margin at the top on the next.

He was then pipped by Reynolds at the flag, the veteran capping off a strong day for Team 18 by topping the session by six-hundredths of a second.

Despite missing out on top spot, Mostert still emerged from Friday as the fastest of the Finals contenders, his closest title rival Broc Feeney fourth fastest behind Anton De Pasquale.

“It’s quite tricky, you don’t know how you feel,” said Mostert. “Track grip is so low here, you’re kind of dancing around. But everyone is dancing around.

“Good confidence-building day for us. Reynolds and De Pasquale are really fast this weekend. We’ve got a bit of tuning to do to make the car a bit better. But the car feels like it’s around the window.”

James Golding was fifth fastest ahead of Cooper Murray, while Will Brown was seventh. The reigning champion missed his opportunity to improve right at the end thanks to a spin at Turn 4 on his final lap.

Cam Waters was one of just three Mustangs in the Top 10 in eighth with Hill shuffled back to ninth and Ryan Wood 10th.

Ojeda ended up 12th for the session ahead of Finals contender Thomas Randle, while Matt Payne and Kai Allen were the worst-placed of those in the title race in 15th and 16th respectively.

Qualifying for Race 1 kicks off at 11:50am local time tomorrow.

Results: Repco Supercars Championship Penrite Oil Sandown 500, Practice 2