Hansen backs 'cool, calm, collected' rookie
Injuries and Sonny Bill Williams' suspension have forced Hansen to chance his arm with his line-up for Saturday, giving first Test starts to fullback Barrett and inside centre Ngani Laumape.
The pair came off the bench for their only other Test appearances, and have played just 70 minutes of international rugby between them.
But Hansen, after naming his side on Thursday, described Barrett and Laumape as faces of the future for the All Blacks.
Jordie Barrett, the younger brother of flyhalf Beauden, was a "cool, calm collected kid and we wouldn't have put him there if we didn't think he was up to it. He wouldn't be put in the position if we didn't trust him," Hansen said.
"Ngani's the guy we see going forward is going to play a big part in our selection process and we've got a lot of confidence in him."
The inclusion of 20-year-old Barrett and Laumape, 24, along with a recall for imposing wing Julian Savea, are the three changes to the All Blacks run-on side after the Lions levelled the series 1-1 with their 24-21 win in the second Test last weekend.
With Barrett taking the fullback slot, Israel Dagg returns to the right wing and the second Test wings Waisake Naholo and Rieko Ioane both drop out of the matchday 23.
The last time the All Blacks put up a rookie fullback against the Lions was in 1977 when Bevan Wilson came in after New Zealand lost the second Test. His penalty-kicking prowess steered the All Blacks to victory in the remaining two Tests of that series.
Hansen denied reports of scuffles in training as tension mounts ahead of the third Test in Auckland, which some players have compared to a World Cup Final. "There were no fights at training," he said.
He also attempted to play down the importance of the game, insisting it would not be the end the world if the Lions seal only their second series win in New Zealand.
"I've heard a lot of stories this week that you'd think the All Blacks have never lost a game and the sky's fallen in" after losing the second Test, Hansen said.
He described the Lions series as "hugely significant" because it only happens once every 12 years.
"But will it define this team, will it define the people in this team? No, because there's a heck of a lot of this story to be written.
"But what it will do, win lose or draw, it will make this team stronger and that'll be good."