The longer Devon Conway is held out of all three formats for New Zealand, the longer Gary Stead and company are hurting their cause.

While that might be an unconventionally sweeping and subjective way to start a match report, it can be objectively stated that the 29-year-old with 18 first-class centuries and three 50s in his first five T20I innings was the levee that stood between the Black Caps and a dramatic top-order collapse.

More than that, it was the key contribution to a comprehensive 53-run win.

His 99 not out off just 59 balls propelled New Zealand to 184-5 in the first T20I against Australia at Hagley Oval, a match held on the 10th anniversary of the devastating Christchurch earthquake.

It was more than enough after Australia were reduced to 19-4 thanks to brilliant new ball spells by Tim Southee and Trent Boult, then 99-8 when the a superb Ish Sodhi (4-28) accounted for the dangerous Mitchell Marsh (45) and Ashton Agar (23) in the space of three balls.

Conway, needing 12 from the final three balls of the innings to score a deserved century, slogged Kane Richardson for six over cow corner, worked him to boundary along the ground and then was desperately unlucky to miss three figures when he creamed a ball straight to the cover sweeper.

In case you were wondering, there was no chance he could have returned for two.

His last five professional T20 innings have returned 99 not out, 93 not out in the Super Smash final, 91 not out, 69 not out and 50 – a staggering return in the most fickle of formats.

There was no sense that anything special was in the works after Australia won the toss and inserted the hosts.

Martin Guptill did nothing to assuage fears that his loss of form has moved from temporary to something more terminal. He watched two deliveries from Daniel Sams pass harmlessly between off stump and the wide line when he was served up a genuine half-volley right in the four-through-covers slot.

A Guptill in any sort of form pumps this through the off side, holds the pose for a second longer than needed, then scratches out his guard again. This version of Guptill is a touch late on it, skews it straight to Ashton Agar in the gully and walks off with one of those wry grins that scream, "What is going on"?

If the under-fire opener was seeking comfort he could reflect on a pleasant streak of 69 innings without a duck in T20Is, stretching back to 2010 when he was part of a top four that was all dismissed for ducks by Pakistan's new-ball attack.

Tim Seifert, who followed a strong international T20 campaign with some dubious form for Northern Districts, failed to fire also, scratching just a single before being bowled by IPL millionaire Jhye Richardson.

A rotten start turned to putrid when Williamson, whose form cannot be queried, bottom edged a nothing ball to be caught behind.

At 19-3 after four overs the game was spiralling out of control for the home side and you could have struck a line through it if Sams had held his position on the boundary and caught a Conway flick that landed just over the rope.

As it was, Conway found a willing partner in Glenn Phillips (30 off 20). The pair had put on 184 together against West Indies earlier in the T20 season. This partnership was 110 runs shy of that record, but it was critical to getting the Black Caps back in the match.

A 47-run partnership with James Neesham (26 off 15) and an unbroken stand of 44 with Mitchell Santner (7 off 5) off just 19 balls provided New Zealand with a total to defend.

Australia's reply mirrored that of New Zealand's, with quick wickets falling in the power play.

Captain Aaron Finch was the first to go, debutant Josh Philippe quickly followed, as did Matthew Wade and Glenn Maxwell.

The visitors needed a Conway, he wasn't available.