Former captain Will Genia has highlighted the enormity of the Wallabies' Newlands assignment, warning that South Africa will be at the height of their physical and mental powers this weekend.

Victory over the Springboks in Cape Town would stand as the biggest Test win of Ewen McKenzie's 14-month tenure, but Genia says Australia will face the same amount of pressure that engulfed them at Eden Park a month ago when massacred by the All Blacks.

The recalled halfback expects the Boks, looking to defend their world No 2 status, to be a different beast to that which faltered in Perth three weeks ago.

The Wallabies haven't won at Newlands since 1992 - losing their past seven Tests there - and were never in the hunt when outmuscled 28-8 in Cape Town last year.

Genia, back from ankle surgery and on track for a spot on the bench, says they must rise to the occasion as much as the home side will.

He hinted the Wallabies were fortunate South Africa were off their game in Perth, succumbing at the death when Rob Horne scored late against 14 men for a 24-23 comeback win.

"The boys can take confidence in knowing they beat them in Australia and can take it to them," the 55-Test halfback said. "But it's going to be hard.

"You look at the South African side that turned up against the All Blacks in Wellington [losing 14-10], that was a completely different team in terms of their approach and their mentality to the one that played the Wallabies in Perth.

"And they grow an extra leg when they go back home, so it's going to be tough.

"Playing in Cape Town against the Springboks is as big as playing the All Blacks in New Zealand."

The Wallabies failed to cope with a New Zealand outfit in Auckland looking to avenge their 12-12 draw at the start of the Rugby Championship and were smashed 51-20.

Australia, who arrived in Cape Town on Monday night after 18 hours in transit, last won in South Africa in 2011 with a gritty low-scoring win in Durban and will need the same tenacity and resolve on Sunday morning (AEST).

Cheetahs breakaway Teboho Mohoj is expected to go head-to-head with Michael Hooper, preferred ahead of Schalk Burger for the spot left vacant by Francois Louw, while Francois Hougaard will start at halfback.

Genia agreed it would be the team's best victory under McKenzie, whose record stands at 11 wins, seven losses and a draw.

"To know you can beat a side like them on their home ground would be a huge boost for the confidence of the group," he said.

"Last year we got taught a lesson over here." - AAP