Roy hit a hat-trick sixes off Mehidy Hasan in the 34th over before he was caught by Mortaza at cover in the very next ball.
However, Eoin Morgan's side, now No 1 in the ODI rankings, have been relentless since, as evidenced by Roy and Bairstow's 128-run stand in 19 overs as Bangladesh's decision to bowl seven overs of Shakib's spin in the first 15 did not fluster the openers.
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But as he gazed out toward the ball while jogging leisurely between the wickets, Roy slammed straight into umpire Wilson, who dropped to the ground.
England had lost their last two World Cup matches against Bangladesh, including the defeat that knocked them out of the 2015 tournament, but they had no such trouble in blustery conditions in south Wales.More news: The Latest Detail In Prince Harry And Prince William's Feud Is Heartbreaking
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"Jonny and I have been doing pretty well together over the last few years so we've got not too much to worry about", man-of-the-match Roy said. A doctor came onto the field to carry out a concussion test on Wilson, who also went off the field during a drinks break for further checks. By the time he holed out to Soumya Sarkar on the boundary rope, Buttler was moving gingerly after hurting his right hip while sprinting a single. Bairstow (51 off 50 balls) and Morgan (35 off 33) also had weighed in as England topped the 348-8 made by Pakistan against the English at Trent Bridge on Monday.
Jofra Archer, admittedly with the aid of a strong wind that was mainly blowing behind him in Cardiff, bowled the fastest opening spell ever recorded by an England bowler in an ODI, averaging 145.89kph (90.7mph).
The former England assistant coach was full of admiration for Roy's brilliant 153 against Bangladesh in Cardiff on Saturday, the fifth time in six one-day worldwide innings he has passed fifty. That left the Tigers on 219-5, and with no hope with 10 overs remaining. Shakib batted with determination to take Bangladesh across the 200-mark in 37th over but once he departed in the 40th over, the match turned out to be nothing more than a formality for the hosts. "But 380 was always against our chase or favor".
Both teams have so far played two matches each and both won their first one and lost the second. England's next game is against West Indies on Friday in Southampton.