Now, after losing our last 2 league games, Chesterfield will be hopeful of subjecting us to another giant-killing.
Pearce told the City website: "Having been through that scenario, where we played reasonably well, had a player sent off for an offence that was later rescinded, having a penalty awarded against us when it was probably not a penalty, you know that things can happen. It's going to be a tough match for us."
City created and missed several chances in Sunday's 4-2 defeat at Blackburn, and Pearce knows his side need to be more clinical at Saltergate if they are to enjoy another cup run this season.
"As the season has gone on, we have created more and more chances," he added. "We've done ourselves no favours by gifting sloppy goals at the other end, but we are creating more so we need to get our noses in front and give ourselves something to hang on to.
"It's a game we have to go out and win. We saw last season the excitement that was generated around the club by the FA Cup run - we need to do that again in both cup competitions this season."