With the series evenly-poised as 2-2, New Zealand managed to chase down Australia’s total with 27 balls to spare at Sky Stadium, opening batsman Martin Guptill top-scoring with 71.
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Australia won the toss and batted first, with young gun Josh Philippe removed cheaply in the Powerplay.
The experienced duo of Aaron Finch and Matthew Wade steadied the ship before the Australia middle order collapsed.
New Zealand spinner Ish Sodhi claimed 3/24 as the visitors registered an underwhelming total of 8/142.
“Australia just lost wickets at important times,” former Australian wicketkeeper Brad Haddin said on Fox Cricket.
“I thought (New Zealand captain Kane) Williamson captained really well, he changed his bowlers, they won big moments.”
In response, Black Caps openers Devon Conway and Guptill pummelled 51 runs from the first six overs to put the hosts in a commanding position.
Guptill took a particular liking to Adam Zampa’s bowling, smacking three sixes off a single over to bring up his half-century.
Their partnership passed 100 before Conway was eventually dismissed by Aussie speedster Riley Meredith for 36.
Meredith then found himself on a hat-trick after removing opposition skipper Kane Williamson for a golden duck, trapped in front LBW.
Guptill eventually departed for 71, but the late dismissal wasn't enough for the Australians to muster a comeback.
Glenn Phillips (34 not out off 16 ball) clobbered another two sixes off Zampa to put the icing on the cake.
Updates
For the second time in two games, Aussie speedster Riley Meredith has removed New Zealand captain Kane Williamson.
The Tasmanian trapped the Kiwi No. 3 on the pads, and Williamson couldn't be saved by a desperate DRS review.
Meredith suddenly finds himself on a hat-trick at Sky Stadium.
Too little, too late…
Australia has finally unearthed a breakthrough in Wellington, with speedster Riley Meredith removing Black Caps opener Devon Conway for 36.
However, New Zealand only requires 37 runs from the remaining 49 balls.
Black Caps skipper Kane Williamson in the new batsman.
New Zealand opener Martin Guptill has brought up a half-century with a booming six off Aussie spinner Adam Zampa.
Guptill needed just 33 deliveries to reach the milestone, his knock featuring five boundaries and four mammoth sixes.
His partnership with Devon Conway has passed 100, and a Black Caps victory seems inevitable.
New Zealand openers Devon Conway and Martin Guptill have pummelled 51 runs from the first six overs to put the hosts in a commanding position.
The Aussies will be desperate for Adam Zampa to register a breakthrough, otherwise this could be a very short run chase.
Australian batsmen seemingly have a problem with facing full tosses.
Marcus Stoinis struggled to score runs off full deliveries during last week's match in Dunedin, and the all-rounder's issues became more apparent on Sunday.
Stoinis was removed by Ish Sodhi for 26 on a full toss, slapping a delivery towards the boundary rider at long-off.
Incredibly, Australian teammate Ashton Agar was dismissed in almost identical fashion the very next delivery.
Sodhi was suddenly on a hat-trick, but couldn't get the third breakthrough.
After managing 5/43 from their final seven overs, Australia finished their innings with a below par total of 8/142.
Matthew Wade was the rock of Australia's innings, but his knock has ended on 44.
Facing Black Caps seamer Trent Boult, Wade chipped a full delivery towards deep mid-wicket, where Martin Guptill claimed a smart catch.
All-rounder Ashton Agar joins Marcus Stoinis in the middle with Australia 4/103.
Glenn Maxwell has managed to smack a full delivery from Mark Chapman directly towards the boundary rider at deep square leg.
He makes his way back to the pavilion for one, leaving the Aussies in a spot of bother at 3/77.
It was also Chapman's maiden wicket in T20 internationals.
Marcus Stoinis joins teammate Matthew Wade in the middle.
Aaron Finch is making his way back to the sheds after a brief cameo in the middle.
The Aussie skipper made 36 before he slapped a short delivery from spinner Ish Sodhi straight to the point fielder.
Glenn Maxwell is the new batsman in the middle, with Australia 2/74 after 10 overs.
Josh Philippe was elevated to top of the order and failed to validate the promotion, trapped LBW for two.
New Zealand seamer Trent Boult fired in a well-directed yorker, and Philippe played all around the full delivery.
"The experiment didn't work," former Australian wicketkeeper Brad Haddin said on Fox Cricket.
Matthew Wade joins his skipper in the middle, with Australia 1/8 in the third over.
Australian captain Aaron Finch has won the toss and elected to bat first.
Every game this series has been won by the team batting first.
The Aussies have named an unchanged team, while the Black Caps has dropped all-rounder Kyle Jamieson.
The Royal Challengers Bangalore picked up Jamieson for AU$2.66 million, but in four T20 matches against Australia, he has taken 1/175 from 15 overs with the ball.
And to rub salt into the wounds, the New Zealander has been brutally been axed for Sunday's series decider.
NZ XI: Martin Guptill, Devon Conway, Kane Williamson (c), Glenn Phillips, Mark Chapman, Jimmy Neesham, Tim Seifert (wk), Mitchell Santner, Tim Southee, Ish Sodhi, Trent Boult
AUS XI: Aaron Finch (c), Matthew Wade (wk), Josh Philippe, Glenn Maxwell, Marcus Stoinis, Mitch Marsh, Ashton Agar, Jhye Richardson, Kane Richardson, Adam Zampa, Riley Meredith