New Zealand took advantage of South Africa's carelessness to win at Edgbaston and leave their beaten opponents facing a World Cup exit.
In his 176th ODI innings, South Africa opener Hashim Amla became the second quickest player to reach 8,000 runs.
A dismal start to the Cricket World Cup has South Africa facing an uphill battle and, even if they keep winning, four "quarter-finals".
New Zealand can boost their Cricket World Cup semi-final hopes and all but end South Africa's top-four aspirations in Wednesday's match.
It is a huge week at the Cricket World Cup for South Africa, who face New Zealand and Pakistan.
Imran Tahir was key to South Africa's first win of the Cricket World Cup against Afghanistan, earning praise from captain Faf du Plessis.
Afghanistan crumbled to 125 all out in Cardiff, with South Africa easily reaching their total for the loss of just one wicket.
South Africa have lost three matches already and only a stunning run of wins will spare them from Cricket World Cup elimination.
South Africa have a mountain to climb at the Cricket World Cup after three defeats and captain Faf du Plessis wants five wins in a row.
South Africa hooker Malcolm Marx will make a short-term move to Japan after the Rugby World Cup before returning to the Lions.