Darren Moore had no complaints about the first-half red card for Reece James at Peterborough but said it changed the complexion of the game after Wednesday’s promising start on the evening.
The Owls boss said: “It was a red card but It changed the balance of the game.
“We were well in the match before the sending off. It changed the complexion because I thought we were on top, Peterborough looked nervous, we had a gameplan and I was pleased with how we started.
“But when they had an extra man they made the most of it in wide areas and they got balls into the box.”
He added: “It’s our first loss of the season but we have to regroup and look towards Saturday. We will analyse everything about tonight but the important thing is our reaction.
“Reece made a decision, it was the wrong decision and he has apologised to the boys in there. But we are all in it together and we will move forward together.”
Moore made four changes from Saturday’s win over Charlton, with skipper Barry Bannan and Josh Windass both on the bench.
He said: “Josh is coming back from a year off, having been injured. Barry, after the game on Saturday, was struggling with illness and suffered heat exhaustion. He didn’t train yesterday and then came back today so we didn’t want to risk him.”