A last-gasp Peter Leven free-kick was enough to give visitors Chesterfield all three points and despite controlling long periods of the game, Rochdale slipped to a damaging fifth successive home defeat.
In a game of few chances the very least the home side deserved was a share of the points, but they again failed to turn possession into chances and chances into goals.
The home side started brightly after just four minutes Adam Rundle seeing his header loop agonisingly wide and five minutes later seeing his wickedly inswinging corner hooked off the line.
A mistake in the home defence gave the Spireites a great opportunity on 29 minutes, but the usually deadly Jack Lester saw his effort very well saved by home keeper James Spencer.
A minute later, from a Kallum Higginbotham cross, Dale striker Lee Thorpe saw his header scrape the crossbar. And in the last minute of the half, from another Rundle corner, Rene Howe saw his overhead effort go just wide.
The home side continued their control into the second half with defender Rory McArdle seeing his effort cleared off the line and then substitute Adam Le Fondre only failing by millimetres to connect with another Rundle cross.
With just two minutes to go the visitors won successive free-kicks on the edge of the home penalty area and from the second of them, skipper Leven fired into the net from 20 yards to re-ignite his side's play-off hopes and further distance themselves in the table from their hosts.