Cameron Hill has paced his first ever Supercar session at Mount Panorama.
The Triple Eight rookie clocked the quickest time, a 2:09.567s, in opening Dunlop Series practice.
The Canberran will also make his Great Race debut with Chris Pither.
Click here for Practice 1 results
Hill’s teammate Declan Fraser, the Super2 points leader, was second, some 0.47s behind.
Matt Payne, another Great Race rookie, was third ahead of Ryal Harris and Angelo Mouzouris.
The session was suspended midway through due to an incident for Super3 leader Kai Allen.
The right front wheel of Allen’s Eggleston Commodore parted company through the Esses.
Allen managed to avoid further incident, but his stricken car required retrieval.
The entirety of the 40-minute session was held in greasy conditions.
Rain had lashed Mount Panorama to Thursday morning, but cleared once track action commenced.
Still, drivers were forced to tip-toe around the circuit as they found the limit.
Jay Hanson set an early flyer, a 2:22.103s, ahead of Zane Morse.
A drying line emerged, and it was Payne who began to find time.
Payne, who will race on Sunday with 2021 Bathurst winner Lee Holdsworth, clocked a 2:16.701s.
It was undercut by Hill’s 2:15.968s, who lowered his own benchmark to a 2:14.233s.
Hill managed to set his time before Allen pulled over at the exit of Forrest’s Elbow.
Replays showed the front wheel parting company with Allen’s car.
Super3 points leader Allen managed to bring the car to a standstill without major damage.
However, the errant wheel, complete with wheel nut, raced down Conrod Straight before coming to a halt.
The incident triggered a red flag as the wheel and Allen’s car were retrieved.
The session resumed with five minutes remaining, and the times tumbled.
However, Hill again emerged fastest, with Payne initially greeting the chequered flag with the second fastest time.
That became third once Fraser improved, with Hill improving further with the only 2:09s lap of the session.
Matt McLean was sixth, some 2.6s off the pace, ahead of Hanson, Aaron Seton and Thomas Maxwell.
Super2 rookie Reef McCarthy, who is substituting for Jaylyn Robotham, rounded out the top 10.
Brad Vaughan was best of the Super3 class in 16th outright on a 2:18.514s.
Robotham and Matt Chahda are sitting out the Super2 round as they cast full focus to their Great Race wildcard.
Super2 and Super3 drivers will return to the track for Practice 2 at 2:40pm local time.