Technically, despite Cruden starting the series against Wales as the All Blacks' first choice first-five, Barrett was the man in possession of the No10 shirt, having worn it in the third test in Dunedin.
That made the decision slightly easier as it's a selection continuation rather than a changing of the guard and the expectation is that Cruden will feature for a period of the test.
In what was viewed as the other near impossible decision for the All Blacks selectors, Sam Cane will start at openside with Ardie Savea among the replacements.
Cane has shown himself to be free of concussion symptoms and his work rate, tackle count and support play are all features that the All Blacks prioritise and want to utilise from the start. No doubt the coaches will look to inject Savea off the bench to give the All Blacks an unpredictable attacking force in the final quarter.
It's a one-two punch that counters the likely presence of Michael Hooper and David Pocock in the Wallaby loose trio on Saturday night.
Injury has ruled out Dane Coles so Nathan Harris wins just his second start at hooker and the relatively unknown Kane Hames is in line to make his debut, having been named on the bench as loosehead cover for Wyatt Crockett.
Hames is in fairytale territory having started the season without a Super Rugby contract. Drafted as a medical replacement by the Chiefs in March, he has won his bench place on the strength of his scrummaging.
Joe Moody is still suffering from a neck injury and with Ofa Tu'ungafasi still developing as a scrummager, the 27-year-old Hames has been given the opportunity of his life.
"This test match will be another stepping stone in the re-establishment of this group on the international stage and we know that Australia will throw everything at us, which is what test rugby is all about," said Hansen.
"With more than 800 test caps of experience in our matchday 23, I'm confident we have the experience to deal with the challenge.
"This week has been about getting our preparation and attitude dead right and, therefore, there's an expectation that this group will bring real intensity, physicality and a high level of skill execution come Saturday.
"We're also playing for the Bledisloe Cup, which, after the Rugby World Cup, is probably the most important trophy we play for. Both teams will be desperate to get their hands on it which will create added pressure. It's about embracing that pressure and taking it on.
"Our attitude has always been - and still is - that we don't hold the Bledisloe Cup by right; we have to go out and earn the right to take it. As a group we're really looking forward to this challenge on Saturday."
All Blacks v Australia, Sydney, 10pm Saturday
15 Israel Dagg
14 Ben Smith
13 Malakai Fekitoa
12 Ryan Crotty
11 Waisake Naholo
10 Beauden Barrett
9 Aaron Smith
8 Kieran Read
7 Sam Cane
6 Jerome Kaino
5 Sam Whitelock
4 Brodie Retallick
3 Owen Franks
2 Nathan Harris
1 Wyatt Crockett
Reserves: Codie Taylor, Kane Hames, Charlie Faumuina, Liam Squire, Ardie Savea, TJ Perenara, Aaron Cruden, Julian Savea.
