Erasmus has made 13 changes to his starting XV from the side who beat New Zealand 43-28 in Baltimore this month to claim the Rugby’s Greatest Rivalry series 3-1.
He has given players who did not feature much in that series a run, but stacked his bench with experienced replacements, including hooker Malcolm Marx.
Erasmus, who has long spoken of his players adapting to feature in different positions, suggested Marx may not come on in the front row.
Johan Grobbelaar will start at hooker, with the versatile Jan-Hendrik Wessels alongside him.
"If Ox Nche comes on, Jan-Hendrik might move to hooker and we've been trying Malcolm on the flank a little bit,” Erasmus told reporters on Tuesday.
Number eight Marco van Staden regularly switches between the loose-forwards and hooker, while captain for the Australia test, Andre Esterhuizen, plays both as an inside centre and flanker.
“If you look at this team, I think it is a really mobile side,” Erasmus said. “Jan-Hendrik, Johan and Zach (Porthen) bring that in the front row. We know what Eben (Etzebeth) always brings, and then you have Franco (Mostert), Paul (de Villiers) and Elrigh (Louw).
“We will have to match Australia in the way they defend, the way they fill the field and the way they like to keep the ball alive through structure.
“In the backline, I think Aphelele (Fassi) has proven himself. Edwill (van der Merwe) fully deserves a chance. Canan (Moodie) and Andre have done some great things for us together as a centre combination, and we all know how well Ethan (Hooker) has played over the last couple of weeks.”
Erasmus is looking forward to reuniting with new Australia coach Les Kiss, who worked with the Springboks in 2001 when Erasmus was still a player.
“Les Kiss and I go back a long way,” he said. “He is a great guy and a very good coach.
“We don’t have a lot of fights or arguments, but we know we are in for a big battle against a team that will certainly want to put down a marker.”