England 5 for 308 (Roy 180, Root 91*) beat Australia 8 for 304 (Finch 107, Stoinis 60, Marsh 50, Plunkett 3-71) by 5 wickets
Scorecard and ball-by-ball details
With an Aaron Finch century at the top of the order, a staunch middle-order partnership and acceleration at the end, Australia seemed pretty well placed at the halfway mark of the first ODI. That expectation was turned dramatically on its head by a rampant Jason Roy, who soared to England's highest ever 50-over score, and in the company of a rejuvenated Joe Root helped England fly to the steepest ever ODI chase on the MCG with seven balls to spare.
If this was the first match of a series lacking much in the way of context, Roy's combination of daring and determination - with a dash of good fortune via numerous skiers that landed safely - will allow England to look optimistically towards next year's World Cup. It was on this ground, of course, where Australia had thrashed England in the opening match of the previous tournament, setting the scene for their ultimate success.
This time around, England showed themselves to be at the vanguard of the new ODI breed, while Australia, with eight losses from their past nine games, look some way off the pace. Steven Smith's side were left with plenty to think about after looking toothless in the face of England's high tempo game. Jonny Bairstow and Alex Hales had fallen early, but Roy was far from perturbed in dictating terms against an Australian bowling attack that seemed flat after a combination of Ashes and Big Bash League duties. By contrast, Roy had barely fired a shot for Sydney Sixers, but came into his own for England.
Well as Finch, Mitchell Marsh and Marcus Stoinis played, they were forced to regather lost ground after the day's English tone was set by a fast and hostile Mark Wood, who made the Australian top order hop around early on after Eoin Morgan sent the hosts in to bat. Wood notably made life difficult for David Warner, and left open the tantalising question of what a difference he might have made to England's Ashes tilt. Adil Rashid was expensive, but produced a pair of teasing deliveries that accounted for Smith and Marsh amid some looser offerings. Moeen Ali completed his overs with admirable economy placed in context by what was to follow.
Having dumped Glenn Maxwell and Matthew Wade from the team in response to a pattern of middle-order failures last year, Australia's selectors would have been pleased by the way Finch combined with Marsh before Stoinis and Tim Paine played with verve in the closing overs. However, they were reminded of how England have become one of the 50-over game's trendsetters in pushing aggressively for runs from a deep batting order, finding a level of freedom that has been maintained even without Ben Stokes.
Roy's determination to punish anything even slightly loose was demonstrated in the very first over of the pursuit, when Mitchell Starc concluded an accurate over with something slightly wider that was hammered through the covers. By the fourth over England had galloped to 47, meaning that even after Bairstow fenced at Starc to do what is now known as a James Vince, edging behind, the momentum stayed with the tourists. Hales' return was brief, bunting an attempted pull shot at Pat Cummins to midwicket, but a tally of 60 after six overs would have been regarded as a decent powerplay in Twenty20, let alone an ODI.
Above all else it meant that Root and Roy could reassess their target without needing to worry too much about finding the boundary every over, even as the latter reached his 50 from just 32 balls. Australia's fielders and many in a crowd of 37,171 cursed their ill-luck as Roy lofted numerous shots barely over the top of the infield, at times landing these blows with the precision of Frank de Boer's long ball to Dennis Bergkamp at the FIFA 1998 World Cup.
Roy had progressed to within nine runs of a century when Adam Zampa fooled him with an excellent wrong-un that brought a frenzied appeal and a raised finger from the umpire Simon Fry. After consulting with Root, Roy reviewed, and was judged to have been playing a shot, bat behind pad, when the ball struck him fractionally outside the line of the off stump. As if to underline the moment's importance, Roy then clumped the very next ball down the ground for six, and Zampa was not a factor thereafter.
So comfortably then did Roy carry on, and so neatly did Root complement him with deft placement and plenty of impetus running between the wickets, that it seemed likely for a time that England might get to the total without further loss. Smith rotated his bowlers without success, and the records started to flow, including the biggest ever third-wicket stand in an ODI at the MCG, Roy's score surpassing Hales' against Pakistan in 2016 as the best for England, and then topping Mark Waugh's 173 against West Indies in 2001 as the biggest 50-over innings in Melbourne.
Ultimately Roy was to fall within sight of victory, and Morgan also came and went, as did Jos Buttler before Moeen Ali finished it with a boundary. Australia's ODI debutant AJ Tye was by a distance the most economical bowler, but the overall lack of threat posed by the hosts' attack contrasted sharply with the way Wood began proceedings.
Sharing the new ball with Chris Woakes, Wood immediately made his presence felt with a series of fast, rising deliveries that challenged Finch and Warner in ways that had not been seen during the Ashes. Wood's short run and piston-pumping action touched speeds up to 149kph, and Warner in particular was made to hop around before a lifter took the shoulder of his bat and looped gently to Root in the slips - how he would have loved to witness such a moment during the Tests.
Wood's speed and trajectory caused further problems for Finch and the captain Smith, who evaded one lbw appeal for a delivery that beat him for pace, on a surface notably more grassy than the one prepared for the Boxing Day Test. However, there was a lack of pressure coming from the other end, as Woakes offered up rather more pedestrian stuff that Finch in particular was able to capitalise upon off both front and back foot.
Smith, too, was quickly into stride against everyone other than Wood, but would slip up unexpectedly against the leg-spin variations of Rashid. The ball after leaving a wayward leg side wide, Smith offered an open face to the googly and the resulting thin edge was clasped by a juggling Buttler. When Travis Head chopped onto the stumps from the bowling of the serviceable Liam Plunkett, Australia were wobbling in a manner familiar across their poorly ODI record in 2017.
But as if to underline how this area had been recognised by Australia both in terms of selection and attitude, Finch and Marsh refused to panic, working the ball around patiently in recognition of the overs remaining, before signalling a phase of acceleration when Marsh hammered Moeen into the members enclosure beyond long on. Moeen missed a half-chance for a return catch off Finch, who was also at the centre of proceedings when England lost their lone review - Rashid pushing hastily for an lbw referral to a wrong'un comfortably sliding past leg stump.
Finch duly went to his third ODI century against England on this ground, and second in as many innings after the opening match of the 2015 World Cup, by swinging Rashid into the crowd with plenty of bottom hand. Both he and Marsh departed soon after, the latter deceived by a well-pitched slider from Rashid, but Stoinis and Paine maintained Australia's momentum with another intelligent partnership in the closing overs, mixing hustle with heave to take the tally past 300.
Their efforts ensured England would need to break all manner of records to achieve victory. Thanks largely to Roy's renaissance, Morgan's men had remarkably little trouble in doing so.