"He's getting older, isn't he? The more you play the game the more vulnerable you are to injury and he's got quite a few miles on the clock," said Hansen. "He's what we call a red-flag athlete. He's at high risk of getting an injury and we have to be smart about the wear and tear on his body and how much [strain] we put him under."
In recent years Carter has suffered Achilles tendon, hip flexor, adductor muscle, hamstring and calf injuries.
So Cruden will begin his 14th test under the protection of the roof at the Dunedin Stadium after much of his work and that of the All Blacks was upset in the fierce Wellington wind and rain on Saturday at the Cake Tin.
Whether he partners Aaron Smith again at halfback, or Piri Weepu, will unfold later in the week but Hansen knew the tough weekend experience would benefit both young players.
"This game will have done wonders for them because you don't want them to play in test matches that are always easy. You want them to be challenged and tonight they were, not so much in a physical sense but from a game understanding sense."
Cruden acknowledged he was a shade match rusty in the 21-5 test victory against Argentina but he had played many times in awkward conditions at the Cake Tin.
"I think I could have been smarter in setting up opportunities to kick and apply pressure that way and try and turn them around a bit more but at the time we did what we thought would work," he said.
Cruden goaled four from seven shots in the wind and rain.
When Liam Messam replaced blindside flanker Victor Vito soon after halftime, Hansen lauded the new man's contribution as "pretty commanding".
The pack had also stood up against a powerful eight and they had to repeat that against the Boks, said Hansen.
