The same is true of Williams, who was outstanding on Friday night. Conrad Smith and Malakai Fekitoa haven't featured yet this season.
"We are trying to juggle," said Hansen. "We are trying to pick the right team and also give people opportunity and rest some other people. In the case of DC and Sonny, they have come off really good games and normally if we were going with a squad of 31, both would be in it.
"Sonny has got a busy schedule so we thought he'd be better having some time at home. We thought DC could do with being at home as well."
The intensity of a full-blooded test in South Africa will provide the selectors with plenty of information about a handful of players they remain unsure about.
It will be an opportunity to see if Barrett or Slade is best placed to run at No10 should anything happen to Carter at the World Cup.
Both are likely to make the 31 because they are incredibly versatile. They are fantastic options to have on the bench, but while Barrett has played first-five all year for the Hurricanes, his best All Black performances have been at fullback.
Sopoaga has possibly been in better form than both but is disadvantaged by his lack of experience at this level. But with his goal-kicking having come good and his confidence sky high, there will be a willingness to get Sopoaga on the field to see what he can do.
The midfield situation is also posing a few questions, as Williams, Ma'a Nonu and Smith would appear certainties, with Fekitoa and Ryan Crotty in a battle for one place, perhaps.
"We are just trying to find what is the best 31," said Hansen.
"We are trying to build combinations and find versatility as well because you can't replace players in the World Cup and then use them again. Once you replace them, then they are gone.
"So we are just building on what we are trying to do as a team and making sure that with a squad of 41 that if we do have to bring people in, then we have had guys who have had a taste of it and understand what it is like and can fit in pretty easily."