“Our bowlers bowled very well on that wicket,” said Seifert. “On the whole, our bowlers have been outstanding this Tri-series.
“For us batters, it’s always nice batting second on wickets like that. You get an upper hand of what the wicket’s going to play like.
“It was a good display from the bowlers and the batters today.”
Playing his second match of the series, Milne struck with his third ball – rooting Proteas skipper Rassie van der Dussen’s off-stump, after being hit over mid-on for four on the previous ball.
From there, South Africa were unable to build any partnerships of significance against the Proteas’ depleted batting line-up, with a 30-run stand between Reeza Hendricks (41) and George Linde (30 not out) the best on offer.
Once Hendricks fell in the 17th over – caught by Michael Bracewell off Duffy – South Africa’s hopes of any sort of defendable target went with him.
In response, Seifert and Conway added a 51-run partnership, taking only 30 balls to add the half-century stand.
Seifert was given a life on zero, when he was dropped at long-off by Andile Simelane off Linde, and made the absolute most of the reprieve, as the opening pair worked the target to less than a run-a-ball needed.
The wicket-keeper took 38 balls to raise his 50, highlighted by his aggression off South Africa’s spinners, and reached his milestone by sending Senuran Muthusamy down the ground for the first six of the innings.
Even as he lost Rachin Ravindra (3) and Mark Chapman (10), Seifert kept his composure and was joined by Mitchell in the 11th over.
From there, the duo were untroubled, as Seifert belted Kwena Maphaka to the long-on boundary to complete the chase, and give the Black Caps their third win in succession under Rob Walter.
The Black Caps will have one final chance to tune up for the Tri-series final, when they meet the already vanquished Zimbabwe on Thursday night.
South Africa 134/8 (Hendricks 41; Milne 2/21, Santner 2/26, Duffy 2/33)
New Zealand 135/3 (Seifert 66 not out; Muthusamy 2/24)
New Zealand won by seven wickets