On the back of their wins over the All Blacks in Chicago in 2016 and in Dublin last year, the Irish had proven their defensive capabilities under defence coach Andy Farrell.
Knowing they could probably meet at some stage in Japan, All Blacks coach Steve Hansen and his coaching group had worked on their strategy to deal with any challenge they might face in the tournament. Central to that has been the two playmaker concept spearheaded by first five-eighths Richie Mo'unga and fullback Beauden Barrett.
Saturday would show how far that ploy had come, Hansen said.
Ireland were a tenacious side who played a structured game. They were good at what they know they were good at and they didn't wander too much off the script, he said.
"They're not a team that give you a lot of opportunities through mistakes.
"They're pretty good at keeping the ball when they keep it and when they kick it they kick it to put pressure on you rather than to give you a free shot, so you've just got to adapt and adjust to what's happening in the game.
"We've made a lot of changes since we last played them so it will be interesting to see if those changes work or not," he said.
Both teams knew what the pressure of quarterfinals success was all about, the All Blacks had been stopped at this stage in 2007 while Ireland had never advanced, and after the full time whistle one of them would be going home again.
"You just hope that it becomes a good game of rugby that excites the tournament, it's not affected by cards and at the end of it no one has got any excuses and as I say you then have to take your fate on the chin," Hansen said.
Choosing the All Blacks team had been made harder because there were the full 31 players to choose from and he felt all players were in form which was a 'pleasing and exciting prospect'.
"However, you can only pick 23. It's like any selection there's got to be some guys that we could all pick and then you come down to your combinations to finish it off and what you're looking for, the style of game you want to play, the style of game you think the opposition are going to play, so they're all factors that come into it," he said.
Hansen said while Ryan Crotty missed out in the midfield it didn't mean to say if the All Blacks were fortunate enough to advance he wouldn't feature in the next game.
"It was just that for this game we felt the combination of Alby [Lienert-Brown] and Jack [Goodhue] and Sonny [Williams] was the one for us," he said.
It was similar at hooker where Codie Taylor would start with Dane Coles bringing his energy later in the game.
"Either way it is a one-two punch and we are pretty fortunate to have two world-class players in that position."
Taylor had been playing well and had taken advantage of the opportunity when Coles was injured last year.
"He stood up, has matured as an athlete but also as a leader," he said.
Jordie Barrett had been named ahead of Ben Smith as back cover with the extra advantage of being a big goalkicker.
Hansen was confident in lock Brodie Retallick's ability to play the full 80 minutes if required, although that was unlikely. He had the ability to come off a long break well, and there was no question he had put the work in.
They also had the ability to inject fresh legs into the game for either Retallick or Sam Whitelock, in Scott Barrett who was a good player in his own right.
"Those fresh legs could be the difference. We're very fortunate with our bench, it's strong and has been for a long time.
"When you look at the experience that's on that bench it does give you a bit of confidence," he said.