"We scored our goals through set plays and good organisation at the front early on.
"We thought the game was over at 3-0 and just wanted to see it out but Vanuatu came on strong in the second half and played really well.
"There are warning signs for us because we have to play better than that if we want to win on Sunday."
Louis Fenton blasted the Oly Whites in front in the fourth minute and James Musa's powerful near-post header doubled the lead and in the ninth minute from an Alex Feneridis corner.
Feneridis had a hand in New Zealand's first three goals as he also provided the looping cross field ball to put Fenton in space for his strike, and then headed down Jason Hicks' free-kick for Greg Draper to make it 3-0 midway through the first half.
Striker Dakota Lucas was still sidelined through suspension with FIFA's disciplinary committee extending his ban to two matches, so Ethan Galbraith lined up alongside Draper in a revamped front pairing.
Elsewhere, the personnel was the same used in New Zealand's opening game against Papua New Guinea.
Louis Fenton nearly had a second goal when his 74th minute header bounced off the goal line and out only for Vanuatu to break and score at the other end through 17-year-old Jean Kaltack.
Sniffing the chance of an unlikely comeback, Vanuatu pressed for more goals and in the 91st minute an unmarked Kensi Tangis side-footted Ivong Wilson's free kick past Jake Gleeson.
The final kicks off at 4pm on Sunday with Papua New Guinea facing Vanuatu in the playoff for third place at 1pm.
- Herald Online