Guptill hit an unbeaten 54-ball 91 as New Zealand overhauled the Zimbabwe score of 159 in 16.5 overs.
Auckland: Martin Guptill overcame a groin strain to slug an unbeaten 91 from 54 balls as New Zealand beat Zimbabwe by seven wickets in their opening Twenty20 international on Saturday, staying unbeaten against the tourists in all forms of the game.
After losing both the one-off Test and all three one-dayers, Zimbabwe put up more of a fight by reaching a competitive 159-8 from its 20 overs and then reducing New Zealand to 15-2.
However Guptill and Kane Williamson combined for a 137-run partnership that steered New Zealand home with 19 balls to spare.
Gutpill carried on the form that saw him score half centuries in the test and each of the three one-dayers.
Zimbabwe lost the one-day internationals by 90 runs, 141 runs and 202 runs but turned in a more competitive performance on Saturday when it won the toss and chose to alter its tactics by batting first.
Captain Brendan Taylor, who made the decision to bat first, also promoted himself to open and may have regretted it when he was bowled for three in the second over, stepping inside a delivery which hit the top of his leg stump.
When Forster Mutizwa was out without scoring in the third over, Zimbabwe was 16-2 and another rout seemed possible. But Hamilton Masakadza, Tatenda Taibu and Elton Chigumbura combined to ensure the tourists reached a solid score on the revamped Eden Park, which hosted the Rugby World Cup final last October.
Masakadza scored 53 from 36 balls and shared a 62-run partnership for the third wicket with Taibu (27) which steadied the Zimbabwe innings. Chigumbura then blasted 48 from 24 balls, including three fours and four sixes, to give the total more substance.
Zimbabwe was 76-2 after 10 overs, faltered a little to be 106-5 after 15 overs, then lacked the final punch that might have taken it beyond 170 and placed New Zealand under some pressure.
"180 to 190 was probably par on that wicket," New Zealand captain Brendon McCullum said.
"Things are going really good for us at the moment. Martin Guptill is in great form and the bowlers really stood up for us tonight as well."
New Zealand suffered early setbacks, losing opener Rob Nicol and McCullum within three balls in the second over bowled by Kyle Jarvis. At 15-2, they were under pressure for the first time in the Test, one-day or Twenty20 series but Guptill's outstanding form remained its bulwark against failure.
He first worked the ball into gaps in the Zimbabwe field and ran strongly, then began to hit out, reaching his half century from 27 balls with four fours and three sixes.
Williamson held up his end, batting 62 minutes and facing 38 balls for his 48 before being run out two balls before the end.
All-rounder Colin de Grandhomme, who played for Zimbabwe A before moving to New Zealand, then came to the crease in his Twenty20 international debut but didn't face a ball before Guptill hit the winning runs.
Jarvis finished with 2-32 as the only successful Zimbabwe bowler.
"Tonight was definitely a notch up from what we produced in the one-dayers," Taylor said. "But when a guy like Martin Guptill gets going it's very hard to stop him."