Auer was set to make his Mount Panorama debut next week as part of Craft-Bamboo's all-Pro Mercedes entry alongside Daniel Juncadella and Nicky Catsburg.
However a huge crash during Thursday practice for the Rolex 24 has left the Austrian with several fractured vertebrae, ruling him not only out of the Daytona race, but the Bathurst 12 Hour as well.
Craft-Bamboo is now engaged in an eleventh-hour effort to secure a replacement to join Juncadella and Catsburg in the three-driver crew.
The likes of factory Mercedes drivers Philip Ellis and Fabian Schiller, who currently don't have Bathurst drives locked in, are expected to be in the frame to land the Craft-Bamboo seat.
According to team boss Darryl O'Young the nature of the Mount Panorama circuit means careful consideration has to be given to the driver line-up.
However, with the event set to kick off next Friday, he expects the team to reach a decision by the end of this weekend.
"It's very unfortunate for Lucas," O'Young told Motorsport.com.
"We wish him all the best. We hope he has a quick recovery.
"It's a big shame because we were looking forward to working with Lucas. He's a great talent and had a great DTM season last year.
"It's quite a complex situation being so close to the race. Bathurst, for me, isn't like any standard circuit. It's quite unique – it's high-speed and narrow. It takes a special kind of confidence to be able to drive there. It takes experience.
"A lot of the tracks we look to for drivers is people who have raced at Macau, or on the Nordschleife. They are the two good comparisons for drivers who suit this type of circuit.
"We've had a lot of communication and contact from pro drivers who are interested to drive. From our side, we're narrowing it down.
"The team dynamic is very important too, it's not just about how quick the driver is. They have to be able to fit into the three-driver team. A good, cohesive aspect is very important.
"I think it will be decided by the end of this weekend. It's crunch time to finalise someone and we're working on it closely with Mercedes-AMG Customer Racing."
The Craft-Bamboo Mercedes is one of nine AMGs entered in the Bathurst 12 Hour, an event record for a single model of GT3 car.
Four of them are Pro entries, the Craft-Bamboo car joined by a Triple Eight car (Shane van Gisbergen, Broc Feeney, Maximilian Gotz), a GruppeM car (Maro Engel, Mikael Grenier, Raffaele Marciello) and reigning winners SunEnergy1 Racing (Jules Gounon, Luca Stolz, Kenny Habul).