The Silver Ferns were pushed all the way by South Africa in their third match of the Vitality Nations Cup, but showed character to maintain their unbeaten record in the competition.
The first match of the weekend at the Copper Box Arena saw Dame Noeline Taurua's side take the spoils 48-41 in front of a sold-out crowd.
After comfortable victories over England's Vitality Roses and Jamaica, this proved to be the world champions' toughest test and required them to dig deep in order to get the job done.
The SPAR Proteas had only ever beaten the world champions once (back in 1995) and, despite finishing on the wrong side of the result, they will take away plenty from the 60 minutes of netball.
As was the case in their opening two matches, Taurua rotated her squad heavily throughout. However, unlike in the previous games, the changes to her line-up often took time to settle.
The opening quarter saw the SPAR Proteas pressure the world champions before the work of Jane Watson and Phoenix Karaka helped New Zealand to create a 14-11 quarter-time lead.
The Silver Ferns started the second quarter with a four-goal run before their opponents re-grouped and Dorette Badenhorst's changes started to pay dividends.
Lenize Potgieter and Ine-Marí Venter changed the picture in attack, Khanyisa Chawane added energy at Centre and Zanele Vimbela mixed things up in their defensive circle.
South Africa clawed it back to 22-18, but didn't capitalise on all of their turnover ball and New Zealand had the strength to maintain a 27-20 half-time lead.
The third quarter, so often known as the 'championship quarter', saw the Silver Ferns lose a quarter for the first time.
Chawane and captain Bongwie Msomi were releasing the ball freely in attack and that lifted the Proteas. In contrast, New Zealand stuttered slightly in their attack-end.
South Africa first pulled it back to level-pegging, however the world champions finished well and clung onto a slender 38-34 lead at three-quarter time.
In the final quarter, the SPAR Proteas missed opportunities to take the match due to a couple of wayward shots, something Badenhorst highlighted later.
"I think that 90 per cent of the time we really played good netball," the head coach said.
"A few disappointments though, as the last few shots didn't fall. We turned enough ball in the last quarter to take the match but that's the game.
"We just need to go and work on our concentration for the last few minutes. Those type of shots, against the best in the world, need to go in."
Sky Sports is your home of netball - every moment of the Vitality Nations Cup is being shown on air and streamed on YouTube. The final match-day is on January 26, with back-to-back play-off matches.