Beauden Barrett remains the first choice All Blacks five-eighth in the opinion of Dan Carter.

It's been one of the hottest debates in New Zealand rugby all year and now the man more qualified than most to pass judgment has spoken.

Dan Carter, arguably the best first five-eighth to ever pull on an All Black jersey, says Beauden Barrett is still the top pick for the No. 10 jersey.

Richie Mo'unga continues to put pressure on Barrett following classy cameos off the bench against Argentina and South Africa in the All Blacks' last two tests.

GETTY IMAGES Dan Carter rates Beauden Barrett as the best first-five in the country but says pressure from Richie Mo'unga makes for healthy competition.

Mo'unga kicked the winning conversion in the All Blacks' 32-30 win over the Springboks in Pretoria on Sunday morning (NZT) when playing at first-five with Barrett switching to fullback when the Crusaders No. 10 came off the bench.

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But Carter told Newstalk ZB Barrett is still the best option to start in the No. 10 jersey.

"He's still the number one 10 but to have the competition with Richie there, and when the time is right in certain games for Beaudie to go to the back and Richie come on and add another string to the backline…it's a really fortunate position the coaches have got with quality players to be able to bring on as replacements and add a little bit to the game when needed. It's the kind of depth and competition you want in a squad.

"For me Beaudie is still the leader in that All Blacks side and what he's achieved in the last three or four years has been incredible.

PHOTOSPORT Richie Mo'unga kicks the match-winning conversion against South Africa.

"To be the number one player in the world the last couple of seasons, he's been great on occasions this year. I think he's really trying to push himself in that leadership role. He's a key part of the All Blacks side," Carter told Newstalk ZB.

Carter, currently playing for the Kobelco Steelers in Japan, said he is enjoying watching Mo'unga's development.

"I'm extremely proud of Richie and the way he's progressed over the last couple of years. I worked with him down at the Crusaders and he's got such a clear head. He doesn't let pressure get to him as we saw in the weekend.

"The fact he's putting Beaudie under a lot of pressure is great," Carter said.