A groin injury to Aaron Mauger has broken up a five-eighth partnership which has found success at provincial, Super 14 and international level.
However, it has allowed McAlister another run-out at inside centre, a position he has adopted for the Blues franchise.
The 24-year-old will start in the number 12 jersey against South Africa, having played outside Carter in last week's 34-27 victory over Australia.
He said: "It was cool, definitely good to run outside the best first five in the world.
"At second five you've got to run the cutter. DC's (Carter) eyes are looking over there, and you've got to run all the forwards, so it's a pretty tough job as well.
"You've got to run them around and tell them what to do."
McAlister believes the win over Australia, which saw them come from behind to defeat the Wallabies, will stand his team in good stead when seeking a first victory in the Republic under Graham Henry.
"The big thing for us is not to panic," he added. "We were down there (at Eden Park) but you didn't see us panic.
"That was a good thing, I think. We knew it was going to come but it was just a matter of when."