Auer was set to partner Daniel Juncadella and Nicky Catsburg in Craft-Bamboo Racing's all-Pro Mercedes AMG for the Intercontinental GT Challenger opener next Sunday.
That was until the Austrian was ruled out of both the Rolex 24 and the Bathurst 12 Hour after suffering broken vertebrae in a nasty crash during practice at Daytona.
That left Craft-Bamboo looking for a last-minute replacement for Bathurst, the team ultimately landing on factory Mercedes driver Ellis.
"Philip Ellis will replace Lucas Auer in the #77 Mercedes AMG Team Craft-Bamboo [entry] for the Bathurst 12 Hour, starting February 3," posted Mercedes-AMG Motorsport on Twitter.
"We continue to wish Luggi a fast recovery!"
Auer, meanwhile, posted on social today for the first time since his accident. Accompanying a video showing him walking with the support of a frame, he wrote: "Guys, thank you so much for all the love and messages. My surgery went very well and I'm doing good.
"Also a big thank you to the amazing medical team for taking such great care of me. I am ready for the next steps of rehab and looking forward to seeing all of you at the track soon."
Ellis joins a host of Mercedes factory and affiliated drivers that will make the trek down under for the 12 Hour this week.
Rolex 24 GTD Pro winners Juncadella, Maro Engel and Jules Gounon will all race at Mount Panorama, spread across seperate entries.
Juncadella will be in the Craft-Bamboo car while Engel will join Mikael Grenier and Raffaele Marciello in the GruppeM AMG.
Gounon, meanwhile, will return to SunEnergy1 Racing as he looks to win a third straight Bathurst 12 Hour, following his triumphs with Bentley in 2020 and then with Kenny Habul's Mercedes squad in 2022.
Maximilian Gotz, meawhile, will join local stars Shane van Gisbergen and Broc Feeney in Triple Eight's all-Pro AMG.
Other big names such as Jamie Whincup, Richie Stanaway, Craig Lowndes and Jordan Love will be spread among the Pro-Am Mercedes in the 28-car field.
The 2023 Bathurst 12 Hour kicks off with practice starting this Friday.
Watch all of the Bathurst 12 Hour action on Motorsport.tv (not available to viewers in Australia or New Zealand).
