Electing to field first, New Zealand came into the crucial contest with a plan.
The Black Caps deployed off-spinner Cole McConchie in the second over to test the South African top order. And the gamble paid off immediately as he dismissed left-handers Quinton De Kock and Ryan Rickelton off successive deliveries to peg South Africa back to 12/2.
In fine form earlier in the tournament, captain Aiden Markram could not steer them clear out of danger. After a 43-run partnership with Dewald Brevis, Markram fell to a superb diving catch by Daryl Mitchell off Rachin Ravindra.
Brevis played a handy knock of 34 and seemed to have the measure of the surface, which was on the slower side. But he did not stay long enough either and ended up chipping the ball straight to cover off James Neesham.
Once reeling at 77/5, Tristan Stubbs and Marco Jansen dragged South Africa back on track with a 73-run partnership off 48 balls. Jansen and Stubbs got stuck into Neesham in the 18th over, plundering 22 runs off it to lend some much-needed momentum to the innings.
Jansen used his long levers and easy power to full effect, and brought up his half-century with back-to-back sixes against Lockie Ferguson. He hit five sixes and two fours to finish unbeaten on 55 off 30 balls.
It was McConchie (2/9) and left-arm spinner Ravindra (2/29) who had helped the Black Caps make early inroads. Pacer Matt Henry also claimed two wickets, while Lockie Ferguson and Neesham chipped in with a wicket each. The water-tight New Zealand bowling line-up kept South Africa in check almost through the innings, save the late charge by Jansen.
