North stars but South Africa pip Wales
James Hook had also gone over for the Welsh as the home side built a 17-9 lead at the interval.
But two tries in three minutes propelled the Springboks into a lead which they did not relinquish despite a swell of late pressure from Wales to end a pulsating contest.
Wales had to make two last-minute changes to their pack, with Andy Powell replacing an injured Dan Lydiate and Gethin Jenkins' failed fitness test handing Paul James a start.
South Africa brought in Francois Steyn to the centres to boost their backline in their only change from the side which beat Ireland last week.
The visitors began with purpose, securing an instant penalty which metronomic kicker Morne Steyn struck firmly through the posts.
But Wales responded well, and a flowing move from the backs culminated with North striding powerfully over the line to score.
There had been much talk about the promise of the 6'4" and 16.5 stone teenager, currently at Scarlets, in the week, and the composure to finish his first chance just five minutes into his international career will only compound it.
Wales were under pressure from the moment they scored, but their gritty defending paid off midway through the first half when they broke and Hook finished an impressive Wales attack.
South Africa had had as much as three-quarters of the territory in the early exchanges but they were cruelly exposed by an overlap on the left hand side which Shane Williams exploited before playing the decisive pass to Hook.
A penalty from either side followed and despite a knock to Shane Williams' shoulder as the half drew to a close the visitors looked ragged and short of ideas against a confident-looking Wales.
Williams was unable to resume in the second half, pictured later in a sling which renders him a doubt for Wales' remaining fixtures.
A Stephen Jones penalty early after the break extended Wales' lead to 11, but Morne Steyn's boot kept the Springboks in touch.
And as the second half continued South Africa finally got into their stride.
Substitute Willem Alberts, making his first appearance for the Springboks, drove over the line after the men in green powered their way into the Wales 22, and Morne Steyn's conversion brought them back within a point.
Moments later, South Africa regained the lead, with captain Victor Matfield dummying and sweeping to the line for the seventh try of his career on the day he made a record 103rd appearance for his country.
Wales might have been shell-shocked to see their advantage overturned so quickly, but they responded immediately when a crossfield kick from Stephen Jones was gathered by North and put down in the corner.
Jones had a conversion chance to restore the Wales lead at 27-26, but he missed from wide on the right by the smallest of margins.
Replacements at regular intervals for both sides interrupted the flow of the game in the final minutes, as did the scrums collapsing regularly despite the efforts of referee Steve Walsh to fix them.
As the clock ran down Wales came tantalisingly close to a winning score - but after 43 minutes of the second half South Africa's dogged defence held firm and poked the ball out to seal a second consecutive narrow win on this season's tour.