RNZ reports a sloppy first quarter by the home side saw the Proteas take a surprise 16-14 lead and forced Silver Ferns coach Janine Southby make two changes to her starting lineup.
New Zealand turned in a much improved second quarter to finally take the lead and go to the halftime break 32-27 in front.
South Africa tried to cling to the Silver Ferns who stepped up the pace in the third quarter to extend their lead to 46-38.
The fourth quarter was dominated by New Zealand who went on to run away with the match by 19 goals, 65-46.
Although the Proteas are ranked fifth in the world compared to the Silver Ferns at number two, Silver Ferns captain Katina Grant conceded the tourists made life difficult for them, particularly in the first half.
"We had to really grind it out ... they were really niggly and I think South Africa did a really good job on us tonight.
"(It was) unorthodox in that first quarter especially and I think our defence ... got caught chasing (the play) a wee bit which is not our style."
New Zealand have now beaten England and South Africa in the series and on Sunday play Australia, a match which is set to decide the series winner.
Grant said they still need to work on "basics and combinations" ahead of that match.
There were several newcomers in the squad and Grant said "It all still feels a little bit new ... despite the time we have had together. It's just little links we need to tidy up on and once they start clicking we'll be a great team."
Despite the slow start to the match Grant said she was impressed with the way the side finished in the final quarter as it showed what they are capable of.