The individuals they are replacing are arguably the best in the world in their positions so they will be battling not only the Pumas today but also comparisons.
TJ Perenara, Liam Squire and Patrick Tuipolotu will start this morning's test in place of Aaron Smith (rested), Jerome Kaino (injured) and Sam Whitelock (bench). That's Aaron Smith, the world's best halfback (and world's best player in the eyes of Wales coach Warren Gatland), Jerome Kaino, one of the hardest hitters and best blindside flankers in the business, and Sam Whitelock, arguably the world's pre-eminent lineout operator and 79-test veteran.
"I know there are going to be expectations to fill that jersey like he does," Squire said in response to taking over from Kaino. "It's a challenge."
It's a challenge coach Steve Hansen wants to expose the trio to, along with others among the nine changes to the matchday 23 from the side who thumped South Africa 41-13 a fortnight ago.
In the case of Kaino, a change was forced on him, but the All Blacks supremo also knows he needs to build depth. He could have opted for Elliot Dixon in the No6 jersey, given Dixon has started a test, but as he said: "We picked Squire because we have seen him play from the bench and we want to see him start a game. We have seen Dixon start and now need to see what he can do off the bench. It's all about a learning process."
The same can be said of Perenara. It's not easy playing understudy to Smith, and Perenara has made 19 of his 23 test appearances coming off the bench. At least today he knows Smith won't get on the park, given Hansen has opted to keep him out of the matchday 23 to ensure he's at his yappy, quick-firing best against the Springboks next weekend.
Perenara has been excellent in the last couple of months, helping the Hurricanes to their maiden Super Rugby title and then providing good impact off the bench for the All Blacks. Both of those outcomes looked remote in June when he was left out of the squad for the three-test series against Wales in June.
"I remember the day [All Blacks manager Darren] Shand called me to say I had missed out," Perenara said. "I was gutted. I felt like I had been playing some decent footy through the year. I still have a lot of room to improve but I feel like I am in a good place now."
Some of that came about through a realisation of what changes he needed to make in a black jersey.
"Playing for the Canes and playing for the All Blacks is two different things. In the past when I came into the All Blacks I tried to do the same things as what I had been doing for the Canes, which doesn't work. It's not what the system or game plan needs."
What the All Blacks need out of Squire today is physicality to match the Argentine forwards. It's what Kaino delivers but it's also a strength of Squire's game. It will be a different experience for him today, with all of his three previous tests off the bench.
"I have been quite lucky over the last couple of months to train alongside [Kaino] so I have been getting tips off him," Squire said.
"[Kaino said] just to back yourself and go for it. You don't want to hesitate when you are out there. Just trust yourself and why you are in this team."