Forwards hold key as Wallabies shift Suaalii to wing

The Wallabies are vowing to match South Africa's physicality so that new winger Joseph-Aukuso Suaalii and company can "do the magic" in Sunday night's Test in Perth.

The Springboks are one of the most feared rugby nations, with their intense physicality key to them landing the past two World Cups.

Australia have slipped to No.7 in the world rankings, and will start as underdogs against world No.1 South Africa despite having home-ground advantage at Optus Stadium.

Star Wallabies back Suaalii is set to shift from outside centre to winger in a notable move by new Wallabies coach Les Kiss.

But Wallabies lock Jeremy Williams is well aware that the best way to get Suaalii and wingers such as Max Jorgensen and Harry Potter into the game is by unleashing fire against South Africa's powerful forwards.

"You're fully aware that it's going to be a physical game, and it's going to be won up front," Williams said.

"We've got to go out there and make sure we nail our processes ... be physical and lead it on that front. And then let guys like 'Potts' and 'Sua' do the magic."

South Africa have made a whopping 13 changes to their starting line-up for Sunday's one-off Test in Perth.

Only lock Eben Etzebeth and winger Ethan Hooker retain their starting roles from the team that beat the All Blacks 43-28 in Baltimore to seal a 3-1 series win in the inaugural Rugby's Greatest Rivalry.

But the Wallabies aren't being fooled into thinking South Africa are wheeling out a second-string side, with the starting line-up still dripping with World Cup winners and experienced players.

Winger Edwill van der Merwe, flanker Paul de Villiers and prop Zachary Porthen are the only Springboks starters with fewer than 10 Test caps.

Williams' opponents in the second row are Eben Etzebeth (146 caps) and Franco Mostert (84 caps), while scrumhalf Herschel Jantjies and flyhalf Handre Pollard return from injury as a star-studded halves pairing.

"They've obviously named quite an experienced team. In the locks they've got (230) caps between them," Williams said.

"I know that we're backing ourselves in the training that we're doing this week, and we know that if we go out there and set the tone physicality-wise, we'll be a good shot."