While the recently concluded Ashes series unfolded at an attritional pace, both sides are likely to approach the next five games in a more cavalier fashion.
Pat Cummins and Mitchell Starc picked up two wickets each.
After his career-best knock, Roy said that the innings was extra special since it was at the historic MCG.
"[His innings against Australia] is on the back of a tough summer but he finished it incredibly well", Morgan said.
"We had that discussion a few days ago, I suggested to him that he shouldn't play, that he should have a break", Bayliss was quoted as saying by British media on Tuesday.
Roy survived being given out and several close calls before eventually being caught for 180 to help guide his side to a five-wicket success to kick-off the five-match series in winning fashion.
"I think we made big strides".
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Hales could be involved for the first time since being suspended for his involvement in an incident in Bristol in September, which saw team-mate Ben Stokes arrested on suspicion of causing actual bodily harm.
"It gave me a bit of a kick to recognise where I'm at, recognise where my preparation is and start building up a platform of getting ready for internationals".
"I haven't been doing too many things too differently, I had a long net session yesterday with a couple of the coaches and was playing the ball a lot later but other than that all my routines have been pretty similar since I've started".
Australia's Aaron Finch also took his place among the game's supporting acts, though his diligent 107 looked more important at the time. "Now and again, someone, I wouldn't say gets it, but knows where I am coming from".
Adam Zampa thought he had the breakthrough when he had Roy given out lbw on 91, but the on field decision was overturned on review.
"On 170 I tried to hit one over mid-off and Root turned round and said, 'What are you doing?"
"They got off to an absolute flyer".
The 27-year-old Roy raced to his fifty off 32 balls but then took another 60 to get his ton - an impressive sign of maturity from the famously hot-headed batsman.
England's Eoin Morgan poses with the trophy after the fifth Royal London One Day International at the Ageas Bowl, Southampton.