Their chase had been made difficult thanks to Devine, who continued her stellar batting form with a third consecutive 50, making her highest international T20 score with a brilliant 77 from 57 balls.
She added 60 for the second wicket with Suzie Bates, who made 23 from 18 before being unluckily run out by a deflection at the non-striker's end. But with the rest of her team unable to do anything more than put Devine back on strike — Devine hit 11 boundaries to everyone else's eight — it was almost a one-woman show, as the 30-year-old scored over half New Zealand's runs.
Just when a maiden century looked possible, Devine was removed with three overs to go by a wild full toss from spinner Sune Luus, as the White Ferns scrapped their way to 153-5.
In response, Amelia Kerr was the Ferns' standout bowler with 1-17 from her four overs, while sister Jess' medium pacers were also restrictive with figures of 0-14 from three on her debut. Seamer Holly Huddleston claimed two wickets, including van Niekerk's, and with one ball left in her over, South Africa needed 17 runs from seven balls.
However, Tryon hit Huddleston's final delivery for six, and despite having struggled in the previous over, Devine backed herself to bowl the decisive deliveries, only to watch on as Tryon and Luus got South Africa home.