The 27-year-old, long known as a brilliant ball-striker, made a polished 120 as England beat world champions Australia by 38 runs to win the second one-day international in Cardiff on Saturday and so take a 2-0 lead in the five-match series.
Roy's innings and a typically quickfire 91 not out from stand-in captain Jos Buttler, deputising after regular skipper Eoin Morgan suffered a back spasm shortly before the toss, took England to a total of 342 for eight.
Australia opener Shaun Marsh made 131 on his Glamorgan 'home' ground but the tourists were still bowled out for 304 with 17 balls to spare. Roy struck an England ODI record 180 against Australia in Melbourne in January this year.
But, after talking with England batting coach Graham Thorpe. he rated Saturday's innings the best of his five ODI hundreds after his side were sent into bat in overcast conditions by Australia captain Tim Paine.
- 'Tempo' -
That Roy has shown he can score hundreds in different styles will be a boost to England as they seek a maiden World Cup title when staging next year's edition.
"I had a long discussion with Thorpey just after I got out and said it was probably my favourite innings -- as far as the tempo of it, the way I knuckled down early," said Roy.
"I went through some difficult patches, but then came out the other side.
"When I wanted to start expanding my game, unfortunately I got out -- but I was still happy." Early dismissal is an occupational hazard for all openers, and certainly for someone as attack-minded as Roy.
The other side of life at the top of the order was there for all to see when he was out for a second-ball duck at The Oval during England's three-wicket win in Wednesday's series-opener.
But Roy was able to play himself in on Saturday while opening partner Jonny Bairstow made a dashing 42.
"I was able to knuckle down and get myself in," Roy said. "(Jonny) is great to watch isn't he at the moment? He's in some incredible form." Roy's latest century came almost a year after he suffered arguably the biggest disappointment of his England career when left out of the same Sophia Gardens ground for a Champions Trophy semi-final loss to Pakistan, the eventual tournament winners.
"It's disappointing to be dropped at any ground," said Roy. "Playing for England is a huge honour.
"I wouldn't say being dropped in that Champions Trophy has anything to do with making any hundred feel any better than the next. It was a big aim of mine to come back after a long winter and start well." Just prior to this current series, England suffered a shock six-run defeat by Scotland in a stand-alone ODI in Edinburgh.
"Obviously, we had that hiccup against Scotland, and then the first game (of this series) I was a bit panicky, a bit wary of where my game was at," Roy admitted.
"But I've put in a lot of hard work over the last two days, and got a few rewards today." This defeat was Australia's seventh in eight ODIs but the form of Marsh was some consolation.
"It's bittersweet," said Marsh. "It was nice to get a few runs but we couldn't quite finish it off there at the end.
"Obviously, it's a disappointing result for us," he added ahead of Tuesday's third ODI in Nottingham.
"We felt like we were in the game right till the end, but unfortunately (we) just weren't good enough."
First Published: June 17, 2018, 10:16 AM IST