Steve Hansen is confident there is more to come from New Zealand after they kicked off their Rugby World Cup defence with an impressive 23-13 victory over South Africa.

The All Blacks had to withstand plenty of pressure in the opening quarter of their Pool B opener in Yokohama, but they seized control of the game in a stunning six-minute spell featuring tries for George Bridge and Scott Barrett.

Although South Africa fought back impressively after the interval, New Zealand were able to remain ahead and extend their streak of never losing a World Cup pool game.

"We're pretty happy with where we're at at the moment," said coach Hansen in his post-match news conference. "Everybody knew that this was going to be a big match and obviously it was. Both teams played very well at times and we're very happy to come out with a win.

"Were we perfect? No. But you're never gonna be at this stage of the tournament and that was the interesting part about this game for both teams.

"You're not in the swing of the tournament and right from the get-go you've got probably the biggest game of the group. We've come out on top. [I'm] very happy that we did, but there's plenty of stuff we can work on."

South Africa coach Rassie Erasmus highlighted New Zealand's discipline as a key factor in the outcome.

"Discipline was always going to be a massive thing for us," said All Blacks skipper Kieran Read.

"South Africa love to build pressure through those penalties and they've got a kicker like [Handre] Pollard who showed right from the outset he can kick from 50 metres.

"It was a conscious decision from us to make sure we didn't give away too many penalties and we probably haven't been as smart throughout this whole year, but we were at a different level today."