Barrett will play his first game since his suspension in partnership with Sam Whitelock and said the players had been made well aware of how referees would be policing the tackle heights during the World Cup.
"There's obviously a fine line and I've learnt from that and keen to move on. The laws are there for a reason to protect players and player welfare so I've been working hard and keen to address those wrongdoings," he said.
He said overcoming what he called 'bad habits' was down to working hard at training so that towards the end of tough halves, when players were fatigued, he could avoid reverting to those bad habits.
He had been working on getting the height of the tackle right and with referees all controlling the games in the same way, the players knew from referee briefings how they would be ruling in games on high shots or foul play.
Regarding the challenge South Africa offered he said they got a lot of momentum from their scrum and lineout, the set-piece and maul.
"Like always we respect them and see that as a big strength of their game so we want to do our best to nullify that part of their game," he said.
Flanker Ardie Savea said the system the All Blacks were using in the loose forwards wasn't so much about having No.6 on his back. He was happy to be on the field and it didn't matter if the requirement was for him to play an openside, blindside or No.8's role.
"It doesn't really matter to me, [I] just go out there and do what is expected in that role in the team," he said.
He was aware the intensity of the World Cup did increase the pressure but he was comfortable with that and would continue preparing as he always did with role clarity top of the pre-game list.
"Being clear, being light on my feet so I just go out there and play with instincts and not second guessing myself, I'm just going out there and playing," he said.
Knowing the South Africans fondness for the physical game, they liked to run hard and direct and it would be the All Blacks job to try and nullify that on Saturday, he said.
"I believe you have to match them or be better and for us we've hopefully got plans for that in the weekend and we'll just have to wait and see," he said.
Prop Ofa Tuungafasi said his role of playing both propping positions was one of continuing to learn and that was helped by the coaching group they had.
During the Rugby Championship he had played at loosehead and he felt he was getting better and better in that position.