Mitchell Santner (top) checks on Mohammad Nawaz after he fell during their T20 match in Christchurch, New Zealand, on Friday. AP

The Black Caps pair scored unbeaten half-centuries in a 139-run stand as the home side reached 159-3 in the 19th over in response to Pakistan's 158-5.

They were forced to mount a rearguard action after Pakistan captain Shaheen Shah Afridi knocked over New Zealand's top order, reducing them to 3-20 in the third over.

Mitchell scored 72 off 44 balls and Phillips 70 off 52, accelerating over the closing stages to complete victory with 11 balls to spare, having begun their partnership in cautious fashion.

New Zealand can wrap up the series 5-0 in Sunday's final match at the same Hagley Oval venue. Pakistan paid for their inability to support opening batter Mohammad Rizwan, who crafted an unbeaten 90 off 63 balls to dominate his side's innings.

Rizwan found ways to keep the score ticking over against a disciplined New Zealand attack, led by seamers Matt Henry (2-22) and Lockie Ferguson (2-27).

The 31-year-old threatened to reach his second T20 international century but was denied the strike over the closing stages of an innings that featured a relatively low percentage of boundaries: six fours and two sixes.

Allrounder Mohammad Nawaz was the only other player to surpass 20 runs, whacking pace bowler Adam Milne for three successive sixes in his final over to post 21 off nine balls.

Babar Azam, who scored half-centuries in each of the first three games, fell for 19 when he skied an attempted pull off Milne in the seventh over.

Pace bowler Afridi had Pakistan right in the contest when he knocked over Finn Allen, Tim Seifert and Will Young cheaply and finished with figures of 3-34.

Allen's wicket was particularly cherished following the opener's sensational 137 in game three on Wednesday.

However, Mitchell and Phillips gradually pulled momentum back in New Zealand's favour and Pakistan potentially blew their last chance at victory when Sahibzada Farhan dropped a straightforward chance in the deep offered by Mitchell in the 14th over.

Agence France-Presse