Of all the selections Steve Hansen and his All Blacks assistants ponder this week in their downtown Buenos Aires hotel, or perhaps in a cafe by one of the grand boulevards, hooker could be the most difficult.
While all the public talk will be about concentrating solely on the challenge the Pumas will provide at La Plata on Sunday, Hansen and Co must also look ahead to what is likely to be the side's toughest challenge of the Rugby Championship and a match which could decide whether the All Blacks defend their title or not - the Springboks at Ellis Park the following week.
To a large extent Dane Coles repaid Hansen's faith against the Springboks at Eden Park after the coach described him as the "future" for the All Blacks at hooker, a description which could have been a hospital pass for someone less mentally tough.
Coles was overshadowed by the physicality and aggression of Bismarck du Plessis when the South African was on the field, and while the Hurricanes player probably didn't impose himself as much as he would have liked around the field or in the set piece, he certainly wasn't daunted by the occasion.
For Hansen, Coles did enough and will be better for the experience. The 26-year-old has time on his side, something Andrew Hore and Keven Mealamu don't, but the pair will play important roles for the All Blacks over the next fortnight against teams who place a high importance on set pieces.
The big question is, can Coles start two matches in seven days against two of the most physical teams in world rugby?
Hore is about to pull the pin on his career at the top level but his physicality and experience would seem to be ideally suited to starting at least one of the next two tests.
Hore wasn't involved in the recent brutal Springboks match, with Mealamu preferred as Coles' back-up. He is therefore due for a run and could get his chance in what will be a noisy and exuberant Estadio Ciudad de La Plata.
Mealamu, who did well after replacing Coles early in the second half against South Africa, will also be fighting hard for a place in the match day squad. The 34-year-old, seen by Hansen as a possibility for the next World Cup as long as his body holds out, is not ready to play back-up to Coles just yet.
Much will be made this week of the crowd on Sunday but a good start like that produced by the All Blacks against the Pumas last year in a test they went on to win 54-15 will quickly silence it, although Argentina loose forward Pablo Matera gave an insight into his team's mindset when he said: "We had the opportunity to return to our homes, to be with our families and friends, rest and recharge for training this week and prepare very hard for the party that is coming."
Something may have been lost in translation there but if the Pumas do beat the All Blacks on Sunday it will be the first time they have managed it in 28 years of trying.
It would be some fiesta and one Hansen definitely doesn't want to happen on his watch.