Fletcher, meanwhile, is confident the players have overcome their nervous start to the Zimbabwe visit.
He believes their twitchy display in Sunday's five-wicket victory in Harare was a result of their difficult build-up to the limited-overs series, when players were stuck in meetings deliberating whether the tour should go ahead instead of getting into the nets.
But Fletcher has sensed a return to their normal intensity and determination in preparation.
"It was very important for them to relax," he said. "We have been sitting in a hotel in Johannesburg and we have got the same thing here when we just go to the cricket ground and then back to the hotel.
"It was important they got out in big groups and relaxed for half a day, because you have to look at the mental side of it. We have come here to play cricket, but you still have to prepare in the right manner to win a cricket match.
"We didn't underestimate Zimbabwe at all. I think the guys were pretty nervous. You can't hide away from the fact that before the game there was a strange feeling in the camp, a mental thing."
England named an unchanged line-up for today's second one-day international in Harare.
That left Worcestershire offspinner Gareth Batty, Sussex's Matt Prior and Simon Jones of Glamorgan still waiting for their first outing of the series.
Zimbabwe brought in batsman Hamilton Masakadza and spin bowler Gavin Ewing became the first rebel to return to the side when he replaced Doug Hondo.