The 10 fastest cars from the combined Pro-Am qualifying session were set to do battle for pole in a single-lap dash later this afternoon.
However a last-minute change has seen the Shootout dumped in favour of a two-part, 10-car qualifying format.
There will now be two 15-minute sessions for the 10 fastest cars, one for cars from positions 6-10 and another for the fastest five.
The change comes following a meeting between the teams before qualifying and was prompted by concerns over the operating window for the Pirelli tyres.
The tyres have generally been taking several laps to reach their preferred temperature range in the cooler autumn conditions, while tyre ovens are banned under the event's temporary Pro-Am rules.
The Bathurst 12 Hour grid will be determined by a different style of Top 10 Shootout this year," read a statement from organisers.
"Following extension conversations with competitors, event organisers have replaced the existing single-car shootout with a pair of 15-minute sessions for the 10 fastest cars from qualifying.
"The revision of the format has been made to ensure ideal operating tyre temperatures can be reached in current conditions.
"The 15-minute window will allow each driver enough time in the Shootout to reach those temperatures and put in at least one flying lap as they compete for the coveted pole position in Sunday’s race."
Provisional pole winner Chaz Mostert backed the late change.
"It's a little bit weird this weekend with GT cars," he said.
"Normally we would have tyre ovens that would help us guys out to bring the tyre in. But a cold Pirelli around here definitely takes a few laps.
"For us to do a Shootout for one lap, we probably wouldn't be able to use green tyres. So it will be a different style of Shootout, but it's still going to be a lot of fun."
The sprint for pole is still being referred to as the Pirelli Shootout and will still start at 4:10pm local time as scheduled.
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