Perch was on the scoresheet in the boilover.
The former Newcastle United midfielder said on BT Sport: "It was just the gameplan we had all week, we've worked on it hard, we've had four weeks to prepare for it and the gaffer's got us geed up for this game.
"It's the FA Cup, I don't think you need to work too hard on getting people geed up, it's the magic of the FA Cup.
"He (Rosler) told us to press them high and get in their faces, and they didn't like it. I think it paid off."
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