Trent Boult has claimed that the atmosphere in Auckland was "unbelievable" as New Zealand beat Australia in a thrilling World Cup match at Eden Park.

Kane Williamson guided the Black Caps over the line in a one-wicket triumph over their Pool A rivals, after Mitchell Starc had threatened to snatch a win for Australia.

Boult, who earlier took five wickets for the Black Caps, admits that the win will live long in the memory.

"It was unbelievable to be honest, to have a crowd like that chanting away right behind us was something pretty special," the seamer, who finished with career-best figures of 5-27, told reporters. "When the wickets fell you couldn't really hear yourself think. It was an amazing atmosphere.

"I've just tried to do what I've been doing in last five or six months, pitch the ball up and try to swing it.

"I got a bit of luck with a couple of drag-ons but it was obviously all go and something I'll remember for a while."

New Zealand are top of Pool A with four wins from their opening four matches.