Skipper Mitch Marsh has singled out Tim David for his efforts in helping Australia to a dramatic final-ball victory over New Zealand in the first T20I between the trans-Tasman rivals in Wellington on Wednesday.

David strode to the crease at 172-4 with Australia still requiring 44 runs from the final 19 deliveries and the equation looked even more bleak following some good bowling from Adam Milne and Tim Southee in the last two overs of a pulsating contest in front of a parochial home crowd.

But David held his nerve to smash three sixes in quick succession and then heaved Southee to the mid-wicket boundary for four on the final ball of the match to clinch an exciting six-wicket triumph for Australia.

While Marsh won the Player of the Match award for his unbeaten 72 from just 44 balls, the Australia captain gave all the credit to David for his late cameo that got the visitors over the line.

"Complete trust in your game and a real confidence to be able to go out there and do that," Marsh said of David's contribution.

"From the moment he came out he was really calm, he knew what we wanted to do and think he's just learning and learning over the last two years.

"You've seen him dominate T20 comps around the world and come onto the international stage and feel at home playing for Australia.

"It's special to watch and (I am) very proud of him.

"Any time you chase down 216 is a great effort, and we just got over the line by the sheer brilliance of Tim David."

It means David has now scored 140 runs in T20I matches this calendar year without being dismissed, with the Australian No.6 having previously contributed knocks of 37*, 31* and 41* during the three-match series against the West Indies prior to his unbeaten 31* from just 10 deliveries against the Kiwis.

It bodes well for David's involvement for Australia at this year's ICC Men's T20 World Cup in June, with the 27-year-old now in the box seat to hold on to that No.6 position in the batting line-up and play the key role of finisher that he has performed so well in over the past month.

It also leaves question marks surrounding where Steve Smith fits into the Australia XI and whether the veteran batter is included in plans for the T20 World Cup in the USA and Caribbean in the middle of the year.

Smith sat out the first match of the series against the Kiwis as Matt Short was once again preferred in the middle-order, but Marsh hinted Smith may return to the side for the second game of the series in Auckland on Friday.

"I'd say he's likely to come in," Marsh said of Smith.

"Heady (Travis Head) and Davey (Warner, his opening partner) were our first choice for this match, but there's no doubt Steve will come into calculations for the next game.

"I understand that it always raises eyebrows when Steve Smith gets left out of a team but we're certainly building towards the World Cup and we'll give lots of guys different opportunities over the next few games."