Richie Wellens felt there were plenty of lessons to take from the pre-season friendly defeat to Sheffield United.
A double from Lys Mousset along with goals from Oliver Burke and Luke Freeman sealed a 4-0 win for the Blades at the Keepmoat Stadium.
He said: “It wasn’t a great evening for us, it was difficult with them having a new manager and not knowing what system we would come up against.
“They changed it up and we struggled to react when they passed through us which is where their goals came from.
“I’m always trying to envisage what we’d be like if we were up against a team in our league, particularly the patterns we’re taking up and the way we look to hurt the opposition.”
Wellens believes his side have to be braver with the ball when the league campaign gets underway against AFC Wimbledon on August 7.
He added: “We didn’t put the ball in the box often enough and played too many open passes which gifted them possession of the ball very easily.
“I want to excite our supporters but we didn’t give them too much to shout about, we had the opportunities to do that but couldn’t take advantage.”