Manager Martin Allen admitted Danny Jackman's sending off had cost Gillingham dearly in the 2-1 defeat to Rochdale.
Andrew Tutte's fortunate strike had Dale ahead on 15 minutes when his cross beat everyone and nestled in the corner before Jackman saw red for a lunge on the goal-scorer.
Bobby Grant doubled the advantage after the break before Danny Kedwell notched a late consolation from the penalty spot. The defeat was Gillingham's first in the league this season.
"We had a go in the second half. We tried our best to get back into it, but we were not good enough in the first half," Allen said.
"All the games so far the players have been outstanding. Showing desire and commitment, and in that first half, for the first time, we dipped below that slightly. I didn't have a go at them in there, but we weren't quite passionate or fast as usual, though with 10 men we went all out for the point.
"I'm disappointed, but not heartbroken at the result. With the sending off, I thought it was going to be a yellow. But that is three sendings off in my time here, so that will have to be something we look at. We haven't been out celebrating when we have done well, so by the same token, we won't be wallowing either. The players will bounce back."