New Zealand got the start they craved, then South Africa took the contest away from them, finishing on 281 for five.
Trent Boult, swinging the ball beautifully, snaffled two wickets, Hashim Amla and Quinton de Kock, inside the first eight overs, which was followed by a fine stifling operation by a blend of Tim Southee, Boult and new man Matt Henry, who did an outstanding job.
He squeezed Faf du Plessis, beat him with one beauty and his first five-over spell cost only nine. In addition, he earned that rarest of beasts, the crowd chanting his name.
Four days ago he was playing for Canterbury in the Plunket Shield. The decision to choose him over original squad picks Kyle Mills and Mitchell McClenaghan was immediately justified.
However, captain AB de Villiers isn't rated the game's best ODI batsman for nothing. His arrival, after Rilee Rossouw had gone to a splendid one-handed catch by Martin Guptill at backward point, put the oomph into South Africa's innings.
Just at a time South Africa might have started getting twitchy - with New Zealand's ground fielding outstanding - de Villiers set about the bowling.
It became apparent New Zealand would face challenges getting through their fifth bowler allocation. To this point in the World Cup, essentially Boult, Tim Southee and Dan Vettori had ensured New Zealand's death bowling would not be tested.
South Africa had an element of good fortune. Rossouw was beaten by a fine ball first up by Boult, but no edge.
De Villiers skied an attempted pull at Southee and it fell at mid wicket, between three converging fielders; and was dropped by Kane Williamson, a ferocious slap to cover and a difficult chance to the fielder's left at shoulder height.
Once into his stride, de Villiers showed his class. Du Plessis, who plodded for a while, became emboldened and their 100 stand was up in 71 balls.
New Zealand had used five different bowlers in successive overs from the southern end.
But the run rate rapidly increased and de Villiers flew past 50 in 32 deliveries shortly before the rain at which point New Zealand were right up against it.
The rain was a godsend to New Zealand in one sense, depriving South Africa of eight overs.
However the South Africans, with five overs left upon the restart, climbed into the bowlers, managed 65 runs. Lefthander David Miller was the key, clouting 49 off just 18 balls. It was a brilliant cameo, just the ticket for South Africa.
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