“The more we practised we realised that the only position the guy plays at eight is at scrums, which happens maybe 13 or 14 times a game.

“General play is probably what happens most and having guys like Pieter, Marco and Siya on the field we really feel Australia is a threat at the breakdown. They really fight hard at the breakdown, and those guys clean out well at the breakdown, and we feel we are going to need that.

“It’s just at scrumming where he is eight. I know I said a couple of weeks ago that Siya is a six and not an eight, but we came to the conclusion that we actually need him there and have Kwagga [Smith] on the bench.”

The world champion Springboks are seeking a fifth successive win against the Wallabies.

Eramus lauded the Wallabies form in the Lions series, and said there were threats from Australia across the field and said the high altitude conditions in Johannesburg could prove beneficial to the visitors.

“If you go through, [Taniela] Tupou, [Rob] Valetini and [Will] Skelton, and those three loose forwards, are pretty impressive. They scrummed really well in the second half against the Lions as well but I think there will be an aerial battle,” Erasmus said.

“At altitude the ball flies a mile so distance kicking will be a thing. Also they’ve got great guys in the air; you know [Joseph-Aukuso] Suaalii, the young boy [Max] Jorgensen, the other winger [Dylan Pietsch] is a really fiery winger who is really competitive, the inside centre [Len Ikitau] is really competitive.

“I don’t think it’s going to be a kicking competition but I think the aerial battle will be a vital one.”

The Springboks have earned headlines for rolling on as many as seven forwards from their bench – which is known as the “Bomb Squad” – but Erasmus opted for a traditional a 5-3 split between forwards and backs.

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The coach did say he would add another forward if the Wallabies go with a 6-2 split when they name their side on Thursday.

“They [Australia] are a physical and well-coached team, and we’ll certainly not underestimate how much those performances [against the British & Irish Lions], combined with their motivation to bounce back strongly against us after the last few results between the teams, and win their first match ever at Ellis Park, will inspire them,” Erasmus said.

South Africa team: 15. Aphelele Fassi, 14. Edwill van der Merwe, 13. Jesse Kriel, 12. Andre Esterhuizen, 11. Kurt-Lee Arendse, 10. Manie Libbok, 9. Grant Williams, 8. Siya Kolisi, 7. Pieter-Steph du Toit, 6. Marco van Staden, 5. Lood de Jager, 4. Eben Etzebeth, 3. Wilco Louw, 2. Malcolm Marx, 1. Ox Nche