Ten-man Gillingham suffered their first League Two defeat of the season at the hands of Rochdale.
Dale went ahead when Andrew Tutte's cross-shot nestled in the far corner.
Danny Jackson was sent off on 30 minutes for a tackle on Tutte, and Bobby Grant drilled home a rebounded shot to make it 2-0 in the second half.
Danny Kedwell converted from the spot, after George Donnelly had brought down Chris Whelpdale, to give the Gills hope but the visitors held on.
VIEW FROM THE DRESSING ROOM
Gillingham manager Martin Allen told BBC Radio Kent:
"We tried our best to get back into it. It wasn't a very good first-half performance, but in the games so far the players have been absolutely spot on.
"First half was the first time we've slipped below the tempo we've played at.
"It was nothing to do with the crowd, it's the players' performance - me and the team. You don't turn up and applaud if you're watching paint dry - it doesn't happen.
"The crowd in the second half were fantastic because of the players' performance. Fair play, second half, with 10 men, we took it to them. We went all out. I'm disappointed but not heartbroken."
Rochdale manager John Coleman told BBC Radio Manchester:
"I'm delighted with the way we applied ourselves today.
"It was probably a little bit more nervy than it should have been. We invited some pressure on but we dealt with it well.
"People must remember that the combined age of our back four today was 73 - we had three 18-year-olds and a 19-year-old.
"They all stood up and were counted. They were magnificent."