Australian paceman Chadd Sayers will make his Test debut in Johannesburg, where South Africa have opted to bat in the series finale.
Peter Handscomb and jet-lagged openers Matthew Renshaw and Joe Burns, who this week helped Queensland lift the Sheffield Shield in Brisbane, have also been called up by the tourists.
The cheating scandal has prompted an overhaul of Australia's XI, with Steve Smith, David Warner and Cameron Bancroft enforced omissions.
Former batsman Adam Voges presented Sayers with his baggy green on Friday, when left-armer Mitchell Starc was ruled unfit.
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Tim Paine became the nation's 46th Test captain but Cricket Australia, reeling from the ball-tampering saga that prompted coach Darren Lehmann to resign, was unable to sort a captain's blazer in time.
"We would have liked to bat too. There's bit of grass on top," Paine said at the toss.
"Chadd Sayers can extract a bit from most wickets.
"It's been a difficult week."
The Proteas hold a 2-1 series lead and are perfectly placed to record their first home Test series win over Australia since the end of apartheid.
The match will be Morne Morkel's last in Test cricket, the veteran bowler having announced he would retire at the end of the series.
Australia XI: Matthew Renshaw, Joe Burns, Usman Khawaja, Peter Handscomb, Shaun Marsh, Mitch Marsh, Tim Paine (capt), Pat Cummins, Nathan Lyon, Josh Hazlewood, Chadd Sayers.
South Africa XI: Dean Elgar, Aiden Markram, Hashim Amla, AB de Villiers, Faf du Plessis (capt), Temba Bavuma, Quinton de Kock, Vernon Philander, Keshav Maharaj, Kagiso Rabada, Morne Morkel.