When South Africa were 97 for four, New Zealand were well in the hunt. However captain and man of the match de Villiers and lefthander Duminy's unbroken 139-run stand decided the match.
There was a sense South Africa's batsmen were pacing themselves and could have put the hammer down earlier if they'd had to, which is not to detract from New Zealand's bowling which kept them honest.
And New Zealand? Captain Brendon McCullum felt his side were not far off what he wanted to see. But the batting was too loose at times - a point de Villiers felt separated the sides.
"I don't think New Zealand, up front, were prepared to put in the hard yards. That maybe was the difference between the sides," de Villiers said.
Three wickets fell for none in eight balls to spiral New Zealand to 68 for five, and only Ronchi's spirit and inventiveness gave them something to defend.
"It was just a lack of craft really," McCullum said of the batting. "We just lacked a little bit of game awareness."
New Zealand did well to take the contest into the penultimate over, although they needed to keep chipping wickets away to maintain some pressure on the visitors, and couldn't.
Targets such as 62 runs off 54 balls and 23 off 24, which once upon a time would have had spectators edging forward in their seats, are now - with wickets in hand - a doddle to players whose pursuit skills have been so thoroughly sharpened by their T20 experience.
De Villiers said although he never felt in on a pitch which called for graft, "personally, I felt it wasn't a bad wicket, and Ronchi showed that".
Ronchi certainly demonstrated his full value yesterday.
"I felt pretty good and relaxed in the situation and tried to stay out there as long as possible," Ronchi said of only his second bat in three months.
Ronchi also gave Dan Vettori's return to the international bowling crease - 10 overs for 43 - a thumbs up.
The teams meet again on Friday at the same venue.
Christchurch's Hagley Oval, venue for the opening World Cup game on February 14, has been officially approved by the International Cricket Council. The ground has received its ICC Warrant of Fitness, the final hurdle ahead of the Boxing Day test against Sri Lanka.
5 things we learned about New Zealand yesterday
Concrete pills?
They lack match hardness. That should be rectified in the next week.
Lucky Luke
Luke Ronchi's batting shapes as an important asset in the second half of New Zealand innings.
Jimmy's no joker
Don't discard Jimmy Neesham as an opener. He is worth more time at the top.
Tough at the top
Yesterday's defeat rammed home that no Kane Williamson or Ross Taylor leaves New Zealand's batting vulnerable.
White lightning
Trent Boult's first ODI for 20 months showed he has transferred his test match cutting edge to the white ball game.
