New Zealand captain Brendon McCullum looked forward to next month's Champions Trophy in the UK with confidence after a five-wicket win in the first one-day international against England at Lord's on Friday.
The Black Caps were whitewashed 2-0 by England in the preceding Test series, suffering several batting collapses including a slump to 68 all out just a few weeks ago in a 170-run first Test defeat at Lord's.
New Zealand held England to 227 for nine on Friday. But at one for two, after both Luke Ronchi and Kame Williamson fell for ducks to James Anderson in the first over of their reply, it seemed they were destined for more Lord's misery.
But a third wicket stand of 120 between Guptill (103 not out) and Ross Taylor (54) revived the innings.
Opener Guptill was the first New Zealand batsman to make a one-day international century at Lord's and only the second Kiwi to do so anywhere in England, after Mark Greatbatch achieved the feat twice in 1990.
Guptill completed only his third hundred in 70 ODIs, off 123 balls with four sixes and eight fours, when he hit the winning runs to give New Zealand victory with 19 balls to spare.
This win put the Black Caps' 1-0 up in the three-match series and lifted their morale ahead of the Champions Trophy, a 'mini World Cup' tournament featuring the world's top eight one-day nations.
"At one for two, I wasn't thinking the top order was firing but Martin and Ross put together a brilliant partnership and showed that under tough circumstances we've got players with a wealth of experience we can call on," said McCullum
"We've got most bases covered as a team...If we can build up some momentum, who knows where we can get to in the Champions Trophy," he added ahead of Sunday's second ODI at Southampton.
An elated Guptill said: "To get a hundred anywhere is special and even better at Lord's."
Meanwhile McCullum praised his older brother Nathan, New Zealand's lone specialist spinner at Lord's after veteran left-armer Daniel Vettori's planned return from a lengthy lay-off was shelved when he re-aggravated an Achilles injury.
Off-spinner Nathan McCullum responded to the challenge with two wickets for 34 runs in 10 overs.
"Dan was going to play but re-aggravated his injury. We found out this (Friday) morning. So Nathan got the tap on the shoulder and did a brilliant job to bowl 10 straight in the middle stages against pretty good players of spin," said Brendon McCullum."
Four England batsmen, including captain Alastair Cook, made it into the 30s but none made more than Jonathan Trott's 37.
"Everyone knows a top score of 37 doesn't win you a game of one-day cricket," said Cook, whose side came from 1-0 down to win 2-1 in the corresponding one-day series in New Zealand earlier this year.
"But a lot of credit to New Zealand as well. Even when we put them under pressure at the start of their innings that partnership between Taylor and Guptill put the balance back in their favour."