A century on debut by Rob Nicol helped New Zealand to a comprehensive nine-wicket win over Zimbabwe in the first ODI at Harare Sports Club on Thursday.
Nicol, 28, made 108 not out as New Zealand chased down a modest target of 232, winning with 39 balls to spare.
Nicol, who played in three Twenty20 internationals before making his bow in the slightly longer form of the game, put on 153 in 29.3 overs with Guptill, who made 69.
He became only the seventh player to score a hundred on his one-day international debut. The only New Zealander to achieve the feat previously was Guptill, who made 122 not out against the West Indies in Auckland.
Zimbabwe captain Brendan Taylor admitted it was a disappointing outcome after he made an unbeaten 128 to enable his side to post 231-6 after suffering a disastrous start in which the home side crashed to 21 for four off 11 overs after winning the toss. Taylor and Forster Mutizwa (69) put on 156 for the fifth wicket.
"To rebuild from where we were this morning was quite tough," said the Zimbabwe captain. "Forster and I did a decent job that way, but 230 was never good enough. We're a better side than this." Opening bowler Doug Bracewell, another debutant for the Black Caps, put Zimbabwe under early pressure, taking the first three wickets to fall.
But Taylor and Mutizwa stopped the rot with a brave stand that took the total to 177 before the latter was caught by wicketkeeper Brendon McCullum off the bowling of James Franklin.
Taylor, a 25-year-old right-hander with a highest ODI score of 145 not out in South Africa last year, continued to sparkle in sunny, slightly cloudy conditions and slammed three sixes in a penultimate over that yielded 21 runs.
