The duo continued to punish the the Pakistan bowlers with Guptill reaching his fifty with a six.
Tight bowling and a slow outfield restricted New Zealand to 37 for one after 10 overs and the pressure started to show by the 20th over as the run rate remained around four an over.
Half-centuries by Kane Williamson and Ross Taylor helped New Zealand to 257 in the face of a sharply improved performance by Pakistan in the field at the third one-day worldwide here today.
Kiwis beat Pakistan by 61 runs under the duckworth-lewis in the first ODI on Saturday.
Hasan Ali (1) fell to a good diving catch by Williamson at mid-wicket before Boult was brought back to clean up Mohammad Amir (bowled for 14) and top-scorer Rumman Raees (bowled for 16).More news: Dog walks 40 miles to find her former owners
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Opener Fakhar Zaman is unable to bat for Pakistan because of a bruised thigh and has been replaced by Imam-ul-Haq, who will play his fourth ODI.
"It looks like a better wicket (than Wellington), that's why we will bat first". Shadab went on to make 52, to match his highest score in ODIs and to drag Pakistan closer to a competitive total. Williamson introduced his spinners early and left-armer Mitchell Santner and leg-spinner Todd Astle prevented Pakistan from rebuilding through the middle of the innings.
"We learnt a few lessons from the last game", Williamson said Friday.
Speedster Lockie Ferguson was also a major contributor with 3-39 from 10 overs.