Eoin Morgan's rapid 89 not out laid the platform for England's 15-run win over arch-rivals Australia in the first one-day international at Lord's here on Friday.
Victory kept alive England's hopes of replacing their oldest foes as the world's top-ranked one-day side and of being number one in all three formats, although they need to sweep this campaign 5-0 to knock Australia off their 50-over perch.
England were struggling when left-hander Morgan, on his Middlesex home ground, came in at 121 for three.
But the former Ireland international, the man-of-the-match, broke the shackles with a 63-ball innings featuring four sixes and five fours to propel England to 272 for five.
He shared stands of 68 with Jonathan Trott (54) and 83 with Craig Kieswetter (25) after Australia had won the toss.
"Conditions were very tough, I thought 277 was par, but we bowled really well," Morgan told the BBC.
"It's been a big turnaround for me since the start of the year and I'm very pleased," said Morgan, currently out of England's Test side.
"It was comfortable at the end, the wicket was getting better, but the guys bowled really well."
Australia, chasing 273 for victory, saw captain Michael Clarke top-score with 61 after opener David Warner had made 56.
But England's bowlers were largely on top, with their four seamers all taking two wickets apiece.
Asked if Morgan had been the difference, Clarke replied: "He played really well, that's for sure. He deserves a lot of credit, he helped England get to a very good total and it was too good for us unfortunately.
"We probably didn't execute our skills at 'the death' as well as we could have. I think they took 80-odd off the last 10 overs.
"And then we lost wickets at important stages of the game where we needed blokes to go on and make big scores."
Australia opener Shane Watson fell for just 12 when he was caught behind off Middlesex fast bowler Steven Finn, although England had to review Pakistani umpire Aleem Dar's original not out decision.
Left-hander Warner and George Bailey settled into a partnership of 76, but that stand ended when Bailey played on to James Anderson.
Warner struck a six and six fours in 61 balls but was unable to go on and edged Anderson to wicket-keeper Kieswetter who, diving to his left, held the first of four catches.
At that stage, both Clarke and David Hussey were on nought.
The run-rate slowed and Hussey made just 13 before a Finn bouncer hit his helmet and deflected onto the stumps to leave Australia 132 for four.
Clarke and wicket-keeper Matthew Wade got Australia back into the game with a stand of 57 at better than a run-a-ball.
Wade pulled Anderson for six and Clarke drove off-spinner Graeme Swann high over the top to seal a 59-ball fifty.
However, a dreadful mix-up saw Wade run out as he sacrificed his wicket on behalf of his skipper.
"It probably played a big part in us not winning the game," said Clarke.
"If Matthew and I were there at the end, we were confident we had a chance.
"It was disappointing and run outs tend to do that, don't they? They tend to cost you the game."
Tim Bresnan then captured the prize wicket of Clarke after the batsman swung across a low full toss and was plumb lbw.
Stuart Broad took two wickets for five runs in six balls to leave Australia 231 for nine.
But Brett Lee and last man Xavier Doherty held on to leave Australia with a target of 21 off the last over, from Finn.
However, Finn kept his nerve and conceded just five runs as England beat Australia in a one-day international at Lord's for the first time since 1997.
The series continues across London at The Oval on Sunday.