Martin Guptill continued his rich vein of form against Zimbabwe as he scored 91 not out to help New Zealand beat the visitors by seven wickets at Eden Park in Auckland Saturday in the first of their two Twenty20 internationals. Guptill blasted five boundaries and six sixes as New Zealand made 160 for three off 16.5 overs after Zimbabwe had scored a credible 159 for eight from 20 overs. Kane Williamson (48) combined with Guptill in a 137-run partnership after Kyle Jarvis had taken two wickets in the second over to put New Zealand under some pressure for the first time on their tour. Guptill, who was dropped on the boundary on 20, and Williamson set about ticking off the runs with Guptill the aggressor. Zimbabwe's tour concludes after the second Twenty20 international at Seddon Park in Hamilton on Feb. 14.