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 international against Australia.

Roy blasted 16 fours and five sixes in a fabulous 151-ball innings, registering England's highest individual score in ODIs and surpassing the previous record knock at the MCG, Mark Waugh's 173 in 2001.

As a result, England was able to comfortably surpass Australia's total of 304-8 and pull off the biggest successful chase in Melbourne.

READ: Remarkable Roy makes maximum impact as England cruises home at MCG

Roy was dropped by England last June after a barren run of form, but made scores of 84 and 96 against West Indies in September after being restored to the team when Alex Hales was suspended for disciplinary reasons

On Sunday, Hales returned at number three, with England's decision to keep Roy at the top of the order alongside Jonny Bairstow paying off handsomely.

Speaking in the post-match presentation, England skipper Morgan said of Roy: "He was always part of our plans, even when we managed to leave him out, which was a tough decision. Coming back in, we all knew that at some stage he would be part of our plans.

"Moving Joe [Root] to four [to accommodate Hales' recall] was quite a big decision and I think it's proved quite profitable today. Our batting line-up looks quite long, which is nice.

"I thought it was incredible from Jason - when he scores runs he's quite imposing at the crease.

"He's done it for quite a while for us. He came through a tough summer with us but finished it incredibly well, and what a way [this was] to start the series."

Roy had a smile on his face as he reflected on taking the record for England's highest innings from team-mate Hales, who made 171 against Pakistan in August 2016.

"He wasn't too happy about that, by the sound of things," said Roy. "It was one of the first things the boys said, about Halesy being pretty ... err ... disappointed! I was going to use another word.

"It was a tough season last season, so to be selected this time was incredibly special. I don't really have too many words right now. It was just a huge honour to be out there for England again and to get some runs on the board."

There was an injury scare for Roy towards the end of his magnificent knock, when he slipped and appeared to hurt his left hand, but he insisted he will be fit to play in Friday's second ODI in Brisbane.

"It'll be ok, it'll be fine. I've heard it's a pretty nice track, so [I'll be playing]," he added.