Rassie van der Dussen gave South Africa something to bowl at as the Proteas struggled to 241 for six against tight bowling from New Zealand while battling for a win they need to keep their fading World Cup hopes alive.
After a soggy outfield delayed Wednesday's start at Edgbaston and reduced the match to 49 overs per side, Black Caps captain Kane Williamson won the toss and chose to field, hoping to take advantage of bowler-friendly conditions.
Hashim Amla made a sluggish 55 off 83 balls but Van der Dussen's 67 not out came at better than a run-a-ball.
New Zealand are unchanged while South Africa have brought in pacer Lungi Ngidi in place of Beuran Hendricks.
Teams:
South Africa: Faf du Plessis (C), Hashim Amla, Quinton de Kock, Aiden Markram, Rassie van der Dussen, David Miller, Andile Phehlukwayo, Chris Morris, Kagiso Rabada, Lungi Ngidi and Imran Tahir.
New Zealand: Kane Williamson (C), Martin Guptill, Colin Munro, Ross Taylor, Tom Latham, James Neesham, Colin de Grandhomme, Mitchell Santner, Matt Henry, Lockie Ferguson and Trent Boult.