Pace bowler Adam Milne claimed four wickets as New Zealand beat Pakistan by 21 runs in the second Twenty20 international Sunday to take a 2-0 series lead.

The tourists threw away a strong position in their run chase after Babar Azam and Fakhar Zaman scored half-centuries as they were dismissed for 173 in the final over, in response to New Zealand's 194-8.

Victory came at a cost for the Black Caps, whose captain Kane Williamson retired hurt with a hamstring injury while batting, placing him in doubt for the remainder of the five-match series.

The match bore similarities to New Zealand's 46-run win in the opening match in Auckland on Friday, with their attack taking wickets at regular intervals to deny Pakistan a foothold in their chase.

However, the target looked within sight before Fakhar was bowled by Milne for a power-packed 50 off 25 balls in the 10th over, leaving Pakistan 97-3.

They struggled from that point, with only Babar looking a threat until he was caught off Ben Sears for 66.

Milne finished with 4-33, having earlier removed the dangerous Mohammad Rizwan as Pakistan lost both openers with just 10 runs on the board.

New Zealand were again asked to bat first and Finn Allen took on the visitors' attack, blasting five sixes in his 74 off 41 balls to dominate the innings.

Well placed at 111 for one at the midway point, the Black Caps suffered a major setback soon afterwards when Williamson was forced to retire hurt for 26.

There will be concern it is a continuation of the spate of injuries the veteran skipper has suffered in the last year.

A long-standing knee problem ruled the 33-year-old out of both white ball series at home to Bangladesh in December.

Allen powered on in trademark big-hitting fashion before being bowled by leg-spinner Usama Mir.

New Zealand's remaining batters struggled, with pace bowler Haris Rauf particularly adept over the closing overs, finishing with 3-38.

Spinner Mitchell Santner replaced seamer Matt Henry in New Zealand's only change from the Auckland match, while Pakistan fielded the same team.