Asked to bowl first, Nasum (4-10) and Mustafizur (4-12) restricted the Black Caps to 93 all out before skipper Mahmudullah (43 off 48 balls) once again led from the front to take his team to the historic win at the Sher-e-Bangla National Cricket Stadium on Wednesday.
Bangladesh bowlers once again exploited the slow-turning surface to deny Black Caps from batting out 20 overs. Nasum and Mustafizur also became the first Bangladeshi bowling pair to grab four wickets each in a T20 game.
The Tigers’ task with the bat was no cakewalk as southpaw Ajaz Patel once again proved lethal with the ball, finishing with a miserly 2-9 from four overs.
Despite tying down New Zealand to a subpar total, there were nervy moments in the chase but Mahmudullah showed steely nerves and launched a six and a four in the space of six balls to power Bangladesh to the win with just five balls to spare.
The series win is Bangladesh’s third in the last three months, coming on the back of a series win over Zimbabwe in Harare and a maiden triumph over Australia at home before it was New Zealand’s turn to concede defeat to an impressive youthful Bangladeshi side.
Nasum was accurate right from the start and maintained his line and length while openers Rachin Ravindra (0) and Finn Allen (12) went for sweeps. The left-arm orthodox spinner eventually got both the batsmen out to dent the tourists' hopes of getting off to a good start.
As Tom Latham (21) and Will Young (46) stitched up a 35-run stand for the third wicket, Bangladesh required a tossed-up delivery from Mahedi Hasan to beat the Kiwi skipper and leave him short of the crease as Nurul Hasan whipped off the bails.
Nasum capitalised on that and went through the gates of Henry Nicholls (1) with one that spun back before Colin de Grandhomme edged back to Nurul for a duck as the Black Caps stuttered to 52 for five in the 12th over.
Mustafizur then followed up Nasum’s double-wicket over by taking two scalps of his own in the 16th over. He sent Tom Blundell (4) back as the batsman miscued over the bowler's head where Mohammad Naim pouched a good diving catch.
In the last delivery of the over, Mustafizur held on brilliantly to a return catch from Cole McConchie (0) who was totally deceived by a ripping cutter from the wily seamer.
Young kept going strong, sweeping and driving for five boundaries and a six in his 48-ball knock. But as the overs and wickets were trickling away, he sent one straight to Mahmudullah at cover.
McConchie took out Liton Das (6) cheaply in the third over to give New Zealand hopes of a fightback and Patel threatened early on. He deceived Shakib Al Hasan (8) with flight, leaving Latham for an easy stumping execution.
Mushfiqur Rahim’s poor run continued when he attempted to sweep the next ball, allowing Patel to creep onto the off stump for two wickets in two balls. As Bangladesh stumbled to 32 for three, in came Mahmudullah.
Opener Naim worked hard for his 29, cracking just one boundary and a six in his 35-ball effort. But he ran himself out while attempting a second and falling short as the chase got tighter for Bangladesh.
When Patel came in for his final over, he managed to go through a charging Mahmudullah, only for Latham to fumble as a stumping opportunity went begging with Bangladesh needing 19 off the last three overs.
Having added 35 runs with Naim for the fourth wicket, Mahmudullah bailed Bangladesh out by clubbing Blair Tickner for a decisive six over midwicket as the hosts rode his knock past the finishing line.
Adjudged Man of the Match, Nasum said: “There was no pressure from the captain. I tried to give as few runs as possible. The wicket was turning, my only focus was to land the ball on one spot.”
At the post-match presentation, Latham said: “We were slightly under par. We were looking at 100-110 but credit to Bangladesh they batted. After a couple of early wickets, they had it under control.
“The way Mahmudullah finished, credit to them. I am pleased with the way we could take it to the last over. Young played a good innings to take us to a competitive score. We lost quick wickets and it was hard to keep the momentum going.
“The way we have been able to adjust slightly on different surfaces, a young group who hasn't played much international cricket, and a lot of us haven't played here, we hope to put in a near-perfect performance in the fifth game.
Mahmudullah said: “The bowlers did a great job once again to keep New Zealand to a low total. All the bowlers, Nasum, Mahedi, Mustafizur, bowled well. The batters tried their best. We just needed a good partnership in the middle and Naim and I tried that.
“Naim batted well and then Afif was good. We tried to build partnerships and take the game deep. The credit for the series win goes to the team management and boys. There is one more opportunity and hopefully, we will regroup together and try to win the game.”