Trent Boult would be used to seeing a field packed with slips and a gully in his first over of a match, particularly for a hat-trick delivery.

Probably not so much in a one-day international.

The 25-year-old had just trapped Scotland's Calum MacLeod and Hamish Gardiner on successive deliveries in New Zealand's World Cup clash with Scotland at University Oval in Dunedin.

With his control of swing and seam position, New Zealand captain Brendon McCullum had packed his field behind the wicket sensing his left-armer could achieve what England's Steven Finn did last Saturday and take a World Cup hat-trick.

The delivery, however, swung too early and Matt Machan was able to leave it and let it go behind to wicketkeeper Luke Ronchi.

"When we get conditions like that where it does swing, and we get that little bit of assistance out of the wicket then the wickets kind of come," Boult told reporters after the tense three-wicket win for New Zealand.

"It's about putting pressure on them and myself in turn trying to keep it as simple as possible."

Boult was named man-of-the match for his opening spell of two for 21 from six overs, though less than six months ago it was debatable whether he would be at the World Cup.

He has been an automatic choice in New Zealand's Test side with his ability to swing the ball both ways at genuine pace.

That seemed to have pigeon holed him as a Test bowler, where he is able to bowl a fuller length and get the ball to do the work for him, and he was picked for just one limited-overs match from November 2012 until October 2014.

He was then recalled for the one-day series against South Africa, which signaled he was in Mike Hesson's World Cup plans and justified the work he had been doing with the white ball.

"Everyone knows that Test cricket is my passion and there is no doubt about that," he said.

There's nothing better than winning a Test match and a Test match series with the black cap on.

"(But) this World Cup was always going to be a big goal of mine and something I'd love to be involved in.

"I felt like I put a lot of focus into the white ball and the game with the white ball in the background.

"So it's nice to be contributing, like I said, and to get some accolades like I have recently is something that I wasn't necessarily expecting."