How does Carter look? Is he taking the ball flat, is he working close to the opposition line and committing those defenders or shovelling the ball on much earlier?
If Carter is the premier five-eighths in the squad he's likely to get Monday's match and probably the final pool game start against Tonga with understudies Beauden Barrett and Colin Slade getting their turn against Namibia and Georgia.
That's the likely plan but injuries will put a huge handbrake on that plan.
This opening test at Wembley will offer a decent gauge on the premier All Black forwards who must contend with a Pumas group confident they can do better than they did in Christchurch earlier this year.
We hear lots about the impact the Pumas will make and they did create a stir when they beat the Springboks in the Rugby Championship before losing back home to the same opposition. Like many sides outside the top level, the Pumas can play well one week then struggle the next.
It is that consistency which separates the elite from the good.
The issue for the All Black selectors will be judging their men against others in the squad because the standard of their opposition will be so varied. How can there be strong comparisons between Monday's men and those who four days later are into combat against Namibia?
Basic skill, sure, and accuracy in the technical departments, but the pressure will be vastly different.
The All Blacks coaches and senior players will ramp up the test with Namibia as a huge exam for the rest of the squad. Maybe, but comparing production in the two matches will be judging passionfruit against potatoes.