A masterful Kane Williamson century propelled New Zealand ahead of South Africa by stumps on day three of the series-deciding final Test in Hamilton on Monday.
It was the 17th ton by Williamson, equalling Martin Crowe's New Zealand record, and featured in a commanding 190-run stand with Jeet Raval for the second wicket.
Raval's dismissal late in the day for 88 triggered a revival for South Africa as New Zealand slipped from 273 for one to 321 for four at stumps in reply to South Africa's 314.
Williamson was unbeaten on 148 with Mitchell Santner on 13.
New Zealand, battling to square the series which South Africa lead 1-0, took control on the third day after rain delayed the start.
Raval resumed with Tom latham who progressed from his overnight 42 to 50 before he was caught behind by a diving Quinton de Kock off Morne Morkel.
It was to be another 58 overs before a second wicket would fall as Williamson joined Raval to dictate the terms to a bowling attack toiling on a flat track.
South African skipper Faf du Plessis had identified Williamson's wicket as a key to beating New Zealand, and the number three batsman showed why as he moved quickly into attack mode, mindful of time lost because of the weather.
Williamson worked the ball to all parts of the ground including a six off Keshav Maharaj over the bowler's head. He followed up with two more off Vernon Philander and Morne Morkel over the square leg boundary — three sixes in one innings from a batsman who only had nine from his previous 60 Tests.