Messam's strong form for Super 15 champions the Waikato Chiefs saw him edge out Victor Vito and Adam Thompson in a position where New Zealand has an embarassment of riches.
Coach Steve Hansen also gave a huge vote of confidence to rookie lock Luke Romano, picking him for Saturday's match in Sydney ahead of emerging youngster Brodie Retallick.
Romano shone in his only previous appearance for the All Blacks, a 60-0 romp over Ireland in June, but was injured in the Canterbury Crusaders' Super 15 campaign and expected to be out of the Rugby Championship's opening rounds.
Elsewhere, the Japan-bound Sonny Bill Williams was named in the centre with Ma'a Nonu after winning a special dispensation from his new club the Panasonic Wild Knights to play in the Championship's two opening matches.
The return of Kieran Read at number eight allows captain Richie McCaw to return to his regular position of blindside flanker, while Cory Jane comes back into the team after recovering from an ankle injury.
The New Zealand team for Saturday's opening Bledisloe Cup match against Australia in Sydney:
New Zealand (15-1)
Israel Dagg; Cory Jane, Ma'a Nonu, Sonny Bill Williams, Hosea Gear; Daniel Carter, Aaron Smith; Kieran Read, Richie McCaw (captain), Liam Messam; Sam Whitelock, Luke Romano; Owen Franks, Keven Mealamu, Tony Woodcock
Reserves: Andrew Hore, Ben Franks, Brodie Retallick, Victor Vito, Piri Weepu, Aaron Cruden, Ben Smith