Ford star Matthew Payne and Triple Eight veteran Jamie Whincup led the times in the opening day's practice sessions for Sunday's Bathurst 1000.
But the talking point of the day was that Whincup's teammate, points leader Will Brown, is looking at a tough weekend after co-driver Scott Pye smashed their Chevrolet Camaro at The Cutting late in the afternoon session.
“Young bloke, cold tyres...” said Pye, after causing the session to be red-flagged.
“I just lost the rear and it was game over. I feel bad for the crew, they will have a long night. It went in pretty hard but at the end of the day, it was my mistake. They have to work hard now to fix my screw-up.”
Payne looked very strong in the morning session with the best lap of the day, a 2m07.29s, leading a Ford 1-2 ahead of Tickford Racing's Cameron Waters. Brown led the Chevrolets in third place ahead of Cameron Hill's Matt Stone Racing entry.
Triple Eight Chevrolets topped the afternoon session, exclusively for co-drivers, which was delayed and then cut short firstly by an oil clean-up from a previous support event and then for the safe removal from the track of what appeared to be a brown snake at Forrest's Elbow.
Whincup led a bloc of five Chevrolets, but not in the way many may have expected. Whincup, a four-time Bathurst winner, edged out rising star Cooper Murray, who is sharing T8's wildcard entry with veteran Craig Lowndes. Jordan Ojeda was third fastest ahead of Erebus Motorsport teammate Todd Hazelwood and PremiAir Racing's David Russell.
It was a big day with an early start in the Ford camp, six of the Mustangs getting new engines fitted with revised, GT3-based crankshafts; both Dick Johnson Racing and Grove Racing cars and one each of the Tickford and Walkinshaw Andretti entries.
The changes were necessary after a rash of unexpected recent crank failures that led to a world-wide search to secure the new Mexican-made units and a hurried 1000km testing program.
The WAU team had a setback on the track as well, with Lee Holdsworth missing most of the final session when the Ford he is sharing with Chaz Mostert was parked with an engine problem.
The Supercars will return to the Mount Panorama track on Friday for two one-hour practice sessions, the first at 10:05am Australian Eastern Daylight Savings Time [12:05am BST], and then at 1:05pm [3:05am BST]. The all-important 40-minute qualifying session, which will set the grid for the 11th to 26th fastest cars, is due to start at 4:15pm [6:15am BST].