"I have huge confidence (in Slade)," said Carter, who will resume his 82-test career in Saturday's Tri-Nations decider against the Wallabies at Suncorp Stadium.
Although the 23-year-old committed a catalogue of fundamental errors during the 18-5 loss, Carter believed Slade still had the requisite skill set and attitude to succeed at test level.
"There's no tougher place to play in South Africa in a test environment like that so he would have learnt a lot from that match. He'll become a lot better player because of it," he said.
"It was an extremely tough game for him. We weren't always getting front-foot ball which makes the job a lot tougher. I still have full faith in him."
The pair had a quick catch-up when the team assembled last night, the crux of Carter's message was: "Don't let it get you down".
"He's still extremely inexperienced at this level but with each game he plays he's only going to get better," he said, adding his door was always open.
"I'll continue to work closely with him and share whatever knowledge I can pass on."
All Blacks head coach Graham Henry admitted Slade's retention was debated before it was decided the keep faith in versatile playmaker.
"Aaron Cruden has been playing superbly in New Zealand and there was a discussion but we believe it's the right decision because he's (Slade) got the all-round skills required in that position."
Slade's proficiency under the high ball was a key attribute particularly as the weather could be less than ideal during the tournament.
"We need a player who's got back field high ball skills that plays 10 because the 10 will drop back into the back field after he's kicked the ball or restarted the game," Henry explained.
Meanwhile, Carter also anticipated a much-improved performance by Wallabies counterpart Quade Cooper when the pair meet for the third time this year at the home of Queensland rugby.
Their much-anticipated duel at Eden Park on August 6 was a no-contest as a Carter master class propelled the All Blacks to a 30-14 victory that retained the Bledisloe Cup.
"I think he'll have a much better performance this weekend," Carter said.
"It was a pretty challenging night for him in Auckland. Our guys were pumped up and played extremely well. We put him and the Wallabies under a lot of pressure.
"I'm sure he'll be more comfortable playing in Brisbane."
Cooper should feel more at home on Saturday considering he enjoyed success against Carter's Crusaders in Super rugby regular season and last month's grand final.
However, he did admit he was guilty of focusing too much on Carter in the build-up to the Auckland test.
"I thought about it too much going into that first game in Auckland," Cooper said.
"At the end of the day, it's the All Blacks versus the Wallabies. It's not myself against Dan, it's not Pocock v McCaw, it's a whole team match-up.
"If you get focused on one player you seem to go missing. If you go in there with a team approach, you turn up with a better mind set."
- NZPA
