Shane van Gisbergen and Matt Campbell were locked in combat at the three-hour mark of the LIQUI MOLY Bathurst 12 Hour.
The pole-sitting #999 GruppeM Mercedes-AMG led the opening stanza via Maro Engel and Mikael Grenier.
However, van Gisbergen took over from Maximilian Gotz under yellow and assumed the lead when the #999 stopped.
The first Safety Car intervention came due to a crash for Stephen Grove across the top of the Mountain.
The #912 Manthey EMA Porsche of Campbell moved to second after stints by Thomas Preining and Mathieu Jaminet.
Campbell, who raced with van Gisbergen in the 2017 Bathurst 1000, was just 0.6s behind the #888 after 73 laps.
Engel led the field to green under darkness, and was followed into Turn 1 by Gotz and Preining.
Griffin’s Bend proved a flashpoint area early on, with Brenton Grove (#4 Porsche) hitting Alex Davison (#222 Mercedes-AMG).
Later, at the same corner, Duvashen Padayachee (#44 Mercedes-AMG) sent Christopher Haase into the tyre barriers.
Padayachee escaped penalty, but significant rear damage forced the Pro Audi out of the race.
All the while, Engel stretched his legs and clocked a 2:02.3540s on his 13th lap. After one hour, his lead was 4.4s.
Behind the leading quintet, the order shuffled around as the Pros battled with Liam Talbot (#65 Audi).
After 30 minutes, Talbot was 25 seconds behind fifth-placed Augusto Farfus (#46 BMW), and a train of cars formed behind him.
Dries Vanthoor moved the #32 BMW forward, and cleared a number of cars — Talbot included — to settle into sixth, albeit 22 seconds behind Farfus.
Ricardo Feller (#777 Audi) was the big mover in the opening hour, moving from 16th to seventh to keep Vanthoor honest.
Feller and Philip Ellis (#77 Mercedes-AMG) were the first contenders to pit 70 minutes into the race on lap 31.
Engel later handed over to Grenier, with Jaminet taking over the #912 Porsche from Preining.
Gotz remained in the #888 Mercedes-AMG and was a reduced 2.6s behind Grenier after 90 minutes.
Kenny Habul (#75 Mercedes-AMG) and Maxime Martin (#46 BMW) had taken over their respective cars and rounded out the top five.
Habul later dropped behind Frederic Vervisch (#55 Audi), Martin and Charles Weerts (#32 BMW), and slotted into seventh.
The big loser after the stops was the #65 Audi — Chaz Mostert took over from Talbot, but was slapped with a drive-through penalty over a pit blend line infringement.
Mostert dropped a lap to the leaders after he took the penalty, and was 13th overall through 90 minutes.
The Supercars star was comfortably the quickest car on the track as he fought to get his lap back.
Mostert caught the battling Mercedes of Grenier and Gotz, and cleared the two AMGs in consecutive laps as the two-hour mark neared.
Vervisch kicked off the second round of stops and handed the #55 Audi to Brad Schumacher.
It came after David Crampton spun the #50 Audi — formerly KTM — into the inside concrete.
The race then took a turn when Grove crashed the #4 Porsche at Brock’s Skyline.
Under yellow, van Gisbergen took over from Gotz, Campbell from Jaminet, Rossi from Martin and Talbot from Mostert.
Grenier stayed out, ceding the lead to the #888 Mercedes-AMG and dropping to sixth at the restart.
Habul, meanwhile, suffered the same penalty as Mostert when he bowled a wide at pit exit prior to the Safety Car.
Habul took his penalty and later handed the #75 over to Jules Gounon at the 2h40m mark.
The first quarter of the race also featured a crash for the #6 Lamborghini at the Cutting, with Adrian Deitz behind the wheel.