Veteran slow-bowler Daniel Vettori was hailed on Sunday as the "unsung hero" of New Zealand's knife-edge one-wicket World Cup win over Australia for applying the brakes on the four-time champions just when they threatened a run rampage.

The 36-year-old, who made his one-day international debut way back in 1997, broke the half-century second wicket stand between David Warner and Shane Watson before tempting Steve Smith to edge a catch behind to Luke Ronchi for just four in Auckland on Saturday.

He finished with two for 41 off his 10 overs -- having had two for 28 off nine -- to move to 298 ODI wickets.

However, Vettori's efforts at Eden Park were overshadowed by left-arm seamer Trent Boult's five for 27 and the explosive batting of skipper Brendon McCullum and Kane Williamson, who hit the match-winning six.

"You've got guys who are good players of spin and they like to attack spin," said New Zealand coach Mike Hesson.

"He (Vettori) controlled his length, just got the drift, occasionally got one to turn and got out two high-quality players. He would probably be the unsung hero."

Boult also hailed Vettori's performance.

"It definitely started off with a hiss and roar on their (Australia's) part," Boult said.  

"Dan came in and did his thing and really tied it up. Not just here, but the work he has done in the past has been crucial to setting up games for us."