Up and coming prop Scott Sio was the latest to go with a suspected ankle syndesmosis, following Tatafu Polota-Nau to the rehab ward after the experienced hooker sustained a low-grade medial ligament injury to his right knee.

Sio was not a starting option for the Wallabies but was being turned from loosehead to tighthead, with the aim of bolstering Australia's limited stocks in the technically demanding position.

His loss and the absence of both Polota-Nau and Stephen Moore, who boast 141 Test caps between them, put extra pressure on the Australian pack, who are preparing for one of the most anticipated Bledisloe Cup showdowns of recent years.

McKenzie was characteristically pragmatic about the situation.

"We've got a number of very good players who are unavailable at the moment. That's just life, you get on with it," he said.

"There's no crisis, that's just the way it is. I'm pretty excited to see how some of the guys step up."

With Sio's experiment at tighthead in mind, the Wallabies called in Rebels prop Laurie Weeks, opting once more to forego bringing in 67-Test veteran, and loosehead, Benn Robinson.

"He's definitely on the radar, we're concentrating on the tighthead prop side of things," McKenzie said.

"There's a bunch of options at loosehead. We still watch, and have been watching, and obviously I think Benn Robinson has been playing pretty well of late. So he's certainly not out of the picture, not at all."

Robinson, who was in rampaging form for the title-winning Waratahs this season, said he was disappointed to have missed out again.

McKenzie did not name the NSW prop in his first Rugby Championship squad a year ago, but brought him in later – at the expense of Sio – after the Wallabies scrum struggled against New Zealand and South Africa.

"I’ve played with the Wallabies for a long time. To miss out is always disappointing," Robinson said at the Waratahs' fan day in Martin Place on Tuesday.

McKenzie also chose not to use the country's most experienced loosehead against France last month, opting instead for impressive Reds prop and Wallabies vice-captain James Slipper.

"We had a conversation around that time," the Wallabies coach said of Robinson. "I've been watching him every week. I think he's been playing better since that time, so he's not out of the picture at all."

Waratahs hooker Tolu Latu is joining the Test side in Bathurst on Wednesday afternoon after being called up to replace his mentor, Polota-Nau.

Force rake Nathan Charles remains the most likely option to start against the All Blacks, with Queenslander James Hanson second in line.

Meanwhile, no one in the Wallabies camp is claiming the advantage after hearing All Blacks five-eighth Dan Carter will miss the first two Bledisloe Cup Tests.

Incumbent halfback Nic White said the New Zealand production line of quality players ensured the All Blacks would not be sweating.

"With Aaron Cruden and Beauden Barrett coming into the side, whatever you lose, they make up for it," White said.

"It's just New Zealand, it doesn't seem to matter. Any time they lose a guy another guy comes in, just as good, to take their opportunity. Beauden Barrett's been pretty unreal off the bench for them and Aaron Cruden has certainly filled Dan Carter's boots the last few times. So they don't lose too much."

McKenzie said it would make coach Steve Hansen's selection choices easier, if anything.

"[They have] an embarrassment of riches there," he said. "Someone was going to miss out so that probably makes it a bit clearer in how they pick it.

"From our point of view, we’re concentrating on ourselves and we’ll play whoever they put out there."