Folau injured his ankle in the opening Bledisloe Cup clash at ANZ Stadium in Sydney.
Dane Haylett-Petty will slot in at fullback with Jack Maddocks promoted to the right wing and Tom Banks earning his start off the bench.
The Folau news is another blow for Michael Cheika’s Wallabies squad, who yesterday announced inspirational back rower David Pocock would miss the fixture with a neck injury.
The Wallabies are back home after losing two Tests against the All Blacks to open their Rugby Championship campaign.
Tonight’s clash will be the 86th Test match between South Africa and Australia, with the hosts having won on 36 occasions.
1. Scott Sio, 2. Tatafu Polota-Nau, 3. Allan Alaalatoa, 4. Rory Arnold, 5. Adam Coleman, 6. Lukhan Tui, 7. Michael Hooper (C), 8. Pete Samu, 9. Will Genia, 10. Kurtley Beale, 11. Marika Koroibete, 12. Matt Toomua, 13. Reece Hodge, 14. Jack Maddocks, 15. Dane Haylett-Petty.
Reserves: 16. Folau Faingaa, 17. Tom Robertson, 18. Taniela Tupou, 19. Izack Rodda, 20. Ned Hanigan, 21. Joe Powell, 22. Bernard Foley, 23. Tom Banks.
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