Steve Hansen has picked Beauden Barrett as New Zealand's fly-half against Australia, while lock Sam Whitelock will win his 100th cap in the Rugby Championship opener.

The form of the Crusaders' Richie Mo'unga in Super Rugby had given Hansen food for thought, but he has opted to select the vastly-experienced Barrett at 10 in Sydney on Saturday.

Barrett, the fourth-highest points scorer in All Blacks history, needs just 18 more to reach the 500 mark for his country.

Mo'unga, who has won just one cap, will not even be among the replacements as Damian McKenzie has been selected on the bench instead.

Centre Jack Goodhue has been picked for just the second time alongside Crusaders team-mate Ryan Crotty, with captain Kieran Read and Brodie Retallick both returning after injury absences. 

Whitelock will follow Read into the 100 club and become just the eighth All Black to reach a century of appearances.

"On behalf of the team, we want to congratulate Sammy on what will be a very special night for him and his family," Hansen said in quotes published on New Zealand's official website.

"We're all very proud of him. He's been an outstanding contributor to this team for a long time, both on and off the field.

"To play one Test for the All Blacks is an achievement in itself but to be good enough to be selected and play 100 Tests is a remarkable feat.

"In doing so, he will join what is a small group of very special All Blacks."