England dropped leg spinner Adil Rashid from their side, with his place effectively taken by Nottinghamshire paceman Jake Ball.
All rounders Ben Stokes (knee) and Chris Woakes (thigh) were both passed fit after missing England´s seven-wicket ODI defeat by South Africa at Lord´s on Monday.
Stokes was initially cleared to be a member of England´s attack after struggling to bowl in recent matches.
"It went all right, I bowled 10 deliveries off a full run this (Thursday) morning," Stokes told Sky Sports.
"There´s no pain there but it doesn´t mean that I won´t feel no pain. It´s a starting point and it gives me confidence.
"Ideally I´d like to get through 10 overs but we´ll see," the right-arm seamer added.
Although a sunny day and a good pitch promised plenty of runs, Morgan´s decision to field first may have been influenced by the fact that Bangladesh were bowled out for just 84 by defending champions India in a warm up match at the Oval on Tuesday.
Bangladesh knocked England out of the 2015 World Cup with a 15-run win at Adelaide and both sides featured several survivors from that match.