New Zealand captain Richie McCaw expressed his delight at having escaped with a win against South Africa after a real arm-wrestle in Dunedin on Saturday.

Dropped scrumhalf Aaron Smith was the hero, coming on to score a game-changing solo try as the All Blacks defeated the Springboks 21-11 in their Rugby Championship encounter.

The win in Dunedin kept the hosts unbeaten after four matches, while the injury-hit Springboks saw their record slump to one win, a draw and two losses.

The win extended the All Blacks' unbeaten run to 14 games as they close in on the world record of 17 Test wins they share with the Boks.

Smith, who had been dropped to the bench for breaking team protocol, was introduced for the second half with the All Blacks holding a slender 5-3 lead.

Then midway through the half, with the scores locked at 8-all, he snapped the deadlock with a brilliant solo try when he darted around the side of a ruck and scampered 30 metres to the line.

The All Blacks scored two tries, to Israel Dagg and Smith, while Aaron Cruden kicked three penalties and a conversion.

South Africa's points came from an exceptional try to Bryan Habana and penalties to Morné Steyn and Johan Goosen.

McCaw said it was "exactly" what they expected from the Boks.

"They certainly played a very physical game and took it to us," the Kiwi skipper said.

I was proud of the guys how they kept their composure ... it was a good old ding-dong."

Although the Kiwis conceded 11 penalties, McCaw did not seem too concerned about his team's discipline.

"Those were long-range penalties," he said, adding: "[Yes], usually those kickers will put them over, so I am thankful; for that.

"[However], towards the latter part of the second half we started to get some control, stuck to our game and started to get a bit of pressure on ... we're just happy with the win."

Asked about his team's defence, McCaw was also very pleased with the team's effort.

"There was a wee patch there were we scored from it, when the guys got the bit between the teeth.

"The defence of both teams were great, making it tough to look after the ball at the breakdown."

The Kiwi skipper also had plenty of plaudits from the impact players off the bench, especially the replacement scrumhalf Smith.

"I think we are pretty lucky with the depth of men we've got, most guys have had a run now and they know what it is all about.

"They slotted in without too much difficulty, so it is great to have that sort of strength.

"I just love this stadium, it is a hell-of-a place to play in.

"It is a good one to remember," he said of the All Blacks' first appearance in the new Dunedin indoor stadium.