New Zealand coach Gary Stead has criticised his team's approach with the bat in the fourth T20I, saying the batsmen did not "fire a shot" at Australia early in the run chase on what was a challenging surface.

Stead acknowledged the game swung significantly Australia's way when Aaron Finch took 26 off the last over from Kyle Jamieson, but felt New Zealand were timid with their response - they were 25 for 1 after the powerplay and then collapsed to 82 for 9 before some late hitting from Jamieson pushed them to three figures.

The surface changed considerably from the first match - this was the fourth game on the surface in three days with the women's series also taking place - which "surprised" Stead but he said the batsmen had been too slow to adjust.

"The disappointing thing for me is I'm not sure we fired a shot at them tonight. When Kyle came in and played the way he did, it was too late then, the game was gone, so we need to think how we do that a little earlier," he said. "In those situations, when it is tough, that was a very good score they had, then you have to try and get ahead of the run rate if you can and that provides a little more opportunity for the middle order to work out the way they need to play it.

"It's that intent to hit boundaries, get on the front foot, even just running between wickets and things like that and I thought we took a step backwards from where we had been earlier in the series. There are things we can do better."

Spinners were effective throughout the game with Mitchell Santner setting the tone, and Stead said that Kane Williamson had considered using himself or Glenn Phillips but did not feel the match-ups were right with Finch still at the crease.

Finch had the advantage of viewing conditions at very close quarters for 20 overs and was quick to hand Ashton Agar the first over of New Zealand's chase with the left-arm spinner bowling three in the powerplay.

"It was one of those days where we got a lot of information out of the way New Zealand bowled and we adapted beautifully," he said. "Ashton Agar was outstanding and all the bowlers were really good."

Finch was often starved of the strike but made the decision reasonably early that he would try and take the innings as deep as possible. "We always knew two new batters on a surface like that was going to be really challenging, especially towards the back end when you expect guys to blast them, it's going to be tough on that kind of surface."

After a poor performance in Christchurch and a narrow loss in Dunedin, Australia now have the chance to clinch the series before quickly packing their kit bags and jumping on a chartered flight back across the Tasman on Sunday evening.

"The fact we were 2-0 down and back to 2-2, really proud of the way we've fought," Finch said. "It's not the first time we've done it, either. It's a really good character test at the best of time because the ebbs and flows are so big."