Eoin Morgan said England always expected Jason Roy to come good again, after the opener compiled a record-breaking 180 to guide his side to an emphatic victory in the first one-day global against Australia.
It is the highest ODI run chase ever at the MCG, exceeding the 296 made by Australia against India in 2016.
Opener Jason Roy recorded the highest-ever one-day global score by an England player as the tourists finally had something to celebrate with a five-wicket win over Australia on Sunday.
The opener had made 84 and 96 in his previous two ODI innings after being restored to England's team when Hales was dropped for disciplinary reasons.
Fast bowler Andrew Tye debuts for Australia and captain Steve Smith, fresh from a remarkable Ashes series with the bat, said he wanted to see an improvement from his team in one-day cricket.
He survived a run-out scare and an lbw decision which was overturned upon review, and lofted several balls just out of the reach of frustrated Australian fielders on the way to his fifth ODI century.
He was eventually dismissed for 106, caught by Jonny Bairstow off a Moeen Ali delivery.
The swashbuckling right-hander lived dangerously throughout his innings, charging along at better than a run a ball and reaching his half-century off only 32 balls.
For Australia, Starc and Cummins scalped two wickets each.
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Set 305 to win, Roy's daring 180 helped England make 308 for five.
"He finally fell to Starc after skying one into the outfield, having faced 151 balls " hitting 16 fours and five sixes.
After being sent in to bat by England captain Eoin Morgan, the home side posted 304 for eight from their 50 overs.
"The middle order's probably where we've had a bit of an issue", Smith said.
"We tried everything we could to pull them back and take wickets but it wasn't our night".
He said: 'It's quite evident when he scores runs he's quite imposing at the crease and today was no different.
"It's been a while coming, I had a very tough year in 2017. being dropped from the side and then being brought back into it towards the end of the year".
Roy was named Man of the Match, and said: "Incredibly special, I don't have too many words right now". "It was one of the first things the boys said, about Halesy being pretty. err. disappointed!"
"It was an absolute honour to be out there on the MCG and to get a score like that, to win our first game of the series is incredibly special".