The debutants have all contributed to the Black Caps' six-wicket win over Bangladesh in the first T20 worldwide in Napier.
Williamson was unbeaten on 73 off 55 balls and smashed 5 fours and 2 sixes while Grandhomme contributed unbeaten 41 off 22 balls hitting 3 fours and 3 sixes as well.
De Grandhomme made an 81-run partnership with his skipper Kane Williamson, as NZ defeated Bangladesh by six-wickets in their first T20 match in Napier. Bangladesh scored 141 for 8 in their allotted 20 overs, to which New Zealand replied with 143 for 4 in 18 overs.
New Zealand swept the 50-over series last week and Bangladesh skipper Mashrafe Mortaza said he was keen for his side to bounce back.
The match looked as if it wasn't going to go the distance after New Zealand's opening three bowlers including debutants Ben Wheeler and Lockie Ferguson tore through the Bangladeshi top order.
Meanwhile, New Zealand captain Kane Williamson said that he would have also opted to bat first.
Sabbir Rahman was first to go, gently lofting a waist-high full toss to Henry at mid-on then Soumya Sarkar was removed for a golden duck after he edged a climbing delivery to Corey Anderson at gully.
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Tom Bruce made his mark on debut when he took a catch to dismiss Bangladesh opener Tamim Iqbal for 11 off his Central Districts teammate and fellow debutant Ben Wheeler.
Ferguson returned to bowl Mahmdullah for 52, just as the veteran batsman threatened to steer Bangladesh to a competitive total.
Mahmudullah then hit 52 off 47 balls with three fours and three sixes to take Bangladesh towards a respectable score.
In reply, New Zealand too lost early wickets, with Neil Broom (6), Colin Munro (0) and Tom Bruce (7) and when the latter fell at the start of the 11th over, the Black Caps were in a spot of bother at 62-4.
But Williamson gave the innings an anchor and de Grandhomme blasted New Zealand home with 12 balls to spare.
"The target was to get some early wickets, which we did, but Williamson batted really well, as did de Grandhomme".