The New Zealand cricketers have lost their third and deciding Twenty20 match at Port Elizabeth.
South Africa cruised to a comfortable 33-run victory at St George's Park to take the series 2-1.
The hosts won the toss and chose to bat first, making 179-6. Opener Henry Davids top scored with 68 from 51 balls.
In reply, the Black Caps could manage only 146-9 from their 20 overs. Martin Guptill, who led the Black Caps to an eight-wicket win in the previous match, hit just 24 while captain Brendon McCullum top-scored with 25.
Cricket commentator Neil Manthorp told Radio New Zealand's Summer Report programme the latest performance was nowhere near the stunning last-gasp win at East London on Sunday.
New Zealand play a three-day match against provincial side Boland in Paarl from 28 December in preparation for the first of two test matches starting in Cape Town on 2 January.