After 92 years... New Zealand finally beat South Africa!

Kane Williamson hit an unbeaten century as New Zealand chased down a victory target of 267 to beat South Africa by seven wickets on the fourth day of the second Test on Friday and clinch a first ever series win over the Proteas.

South Africa, severely depleted with most of their top players back home playing the SA20 tournament, battled hard but were unable to make sufficient inroads into the home batting order.

Williamson's patient 133, his 32nd Test century, mostly came in a partnership of 152 with Will Young (60 not out) that got the Black Caps over the line in what was a record fourth-innings run chase in a Test at Seddon Park.

The 2-0 series triumph will come with a hefty asterisk due to the inexperience of the South African squad and Neil Brand's tourists will take great credit for taking the contest down to the wire after losing the first Test by a thumping 281 runs.

"It was a pretty old fashioned sort of ding-dong Test match," said New Zealand skipper Tim Southee.

"Kane played an absolute blinder, as he has done for so many years, and he was well assisted by Youngy today."

The hosts resumed on Friday on 40/1 with the match very much in the balance after Devon Conway had been dismissed by spinner Dane Piedt in the final over of play on day three.

Opener Tom Latham added nine runs to his overnight tally before he departed for 30, caught by Zubayr Hamza off Piedt, but that just brought Williamson to the crease.

The master batsman boasted an average of 88 in Hamilton coming into the match and he set about constructing his innings in his usual deliberate manner, with plenty of grind but ruthless punishment for anything loose.

The Black Caps reached lunch at 107/2, still 160 runs from their target, and Rachin Ravindra was winkled out by Piedt for 20 soon afterwards when his attempted drive went straight to Brand.

Williamson reached his 34th half-century two overs later, however, and Young survived a scare when he was given out to Shaun von Berg but a review overturned the decision and denied the South African his first Test wicket.

New Zealand scored only 66 runs in the second session to reach tea on 173/3 but Williamson was soon celebrating another century in trademark subdued fashion after a lengthy wait on 99.

The 33-year-old, who scored hundreds in each innings in the first Test, moved alongside Australians Steve Waugh and Steve Smith in joint 11th place in the all-time list of Test century scorers.

South Africa continued to create half chances but seamer Dane Paterson and spinner von Berg enjoyed little luck and finished wicketless, while Piedt had to be satisfied with 3-93 to add to his five-wicket haul in the first innings.

Young slapped a four straight back over the bowler to secure his seventh Test half-century and get the deficit down to a couple of dozen runs but fittingly it was Williamson's 12th four that secured the winning runs.

"Definitely more disappointed after this test match just because we were in the game," said Brand, who was playing his first Test series.

"It was an awesome experience. The first Test was really difficult and I was very proud of the way that we bounced back from this series."

New Zealand moved to the top of the ICC World Test Championship standings with their first-Test win in Mount Maunganui and next host reigning WTC champions Australia in a two-match series starting in Wellington on February 29.