'Immense in all aspects': Skelton's start timely for 'aggressive' Wallabies pack

Scrum coach Neal Hatley has urged the Wallabies to be the aggressors in the ultimate litmus test, taking on South Africa at Loftus Versfeld.

The Australians wrapped up preparations for the opening Rugby Championship clash in Pretoria, with co-captain James Slipper, who suffered a knee injury through the week, cleared to play.

Part of England's World Cup campaign, Hatley joined his former coach Eddie Jones in the Wallabies camp in May and said the team were ready for the challenge at Loftus, where they have never won in 60 years.

Hatley said the forwards needed to stand up to the world champions on their home turf.

"There's not many places harder in world rugby to come than the Springboks at Loftus, so it will give us a good benchmark of where we are," Hatley said.

"You have to be aggressive, you have to be competitive at scrum, and at the line-out and in the drive.

"If you come over here and you roll over, you'll get murdered so we've got to make sure that we are aggressive in all those aspects."

Playing 24 Tests over nine years, towering lock Will Skelton has been named for a rare start and has spoken of his desire to translate his trophy-winning form with French club La Rochelle to the Wallabies.

Hatley said he'd been impressed by the 31-year-old, who had lost weight from his 140kg frame.

"He has been immense in all aspects; his physicality, his size, so it's brilliant to have him," said Hatley, a former prop who played 193 matches in the English Premiership.

"It's been great to have him, he's trimmed down a bit ... and he's come in a had a huge impact on the group because he's been winning over the last two or so years."

The Springboks will be without some of their first-pick forwards including hooker Malcolm Marx and lock Eben Etzebeth after splitting the squad with one group already travelling to New Zealand to prepare for the All Blacks Test.

Captain Siya Kolisi was among them although won't play as he recovers from a knee injury, with veteran back-rower Duane Vermeulen leading the team in Pretoria before flying out.

Hatley said it was a luxury South Africa could afford given their depth, particularly in the forwards, with the Springboks bench labelled the "bomb squad".

Australia have named debutant Tom Hooper at blindside flanker while 21-year-old prop Zane Nonggorr and lock Richie Arnold could play their first Tests from the bench.

"The Springboks have some real problems haven't they - no Malcolm Marx, but they have Mbongeni Mbonambi," Hatley joked.

"Look, they've got incredible depth - we know from a tight five point of view, their bomb squad and we respect the South African pack immensely.

"That's why for us it's an exciting challenge to start with - to play this team, this pack of forwards, at this ground.

"For some of the guys making their debut, to experience Test rugby at altitude in Pretoria against the Springboks is a hell of way to start."