OXFORD United had nothing to show for a largely positive performance as two late goals gave Rochdale all three points.
It was a harsh scoreline on the U's, who for long spells had looked comfortable at Spotland.
But despite creating several chances they could not find a way past Dale goalkeeper Josh Lillis.
The home side took full advantage in the closing stages, as goals from substitute George Donnelly and Bobby Grant proved the difference.
United's starting line-up showed just one change from Saturday's 5-0 demolition of Accrington Stanley.
Lee Cox dropped out of the squad and was replaced in midfield by Peter Leven, while skipper Jake Wright, back from suspension, had to make do with a place on the bench.
The game exploded into life right from the kick-off, with Jason Kennedy testing U's goalkeeper Ryan Clarke with a shot after just six seconds.
United promptly went up the other end and Tom Craddock saw a shot deflected wide.
The striker was full of confidence following his four goals last weekend. He had no hesitation in taking on a tricky half volley from James Constable's lay-off in the third minute, but it whistled just over.
United were bright in the opening 45 minutes and enjoyed the best of the chances.
Their clearest sight of goal came midway through the half, when Alfie Potter should have put them ahead.
The winger latched on to Craddock's scuffed shot, but somehow fired wide of Lillis' right-hand post from close range.
Most of United's best moments came down their left flank, where Tony Capaldi and Sean Rigg got the better of Andrew Tutte and Joe Rafferty.
Their industry helped the U's win a succession of corners, where Johnny Mullins was twice denied by Lillis.
Dale, who had lost their previous two games, struggled to exert any sustained pressure but did threaten periodically.
Clarke tipped a dipping Rafferty shot over the bar, while he was relieved to watch a skidding 25-yard drive from Tutte fly just wide.
Late in the half Michael Raynes picked up his fifth booking of the campaign, which will earn him a one-game suspension this weekend.
The centre back almost scored in the first minute of the second half when he leapt highest at a corner, but Dale cleared off the line.
Dele Adebola was proving a handful at the other end and the veteran striker set up a good chance for Ryan Edwards, who nodded wide just before the hour mark.
They had a better chance on the break minutes later following a loose pass from Jake Forster-Caskey.
Raynes was unable to cut out the through ball which sent Grant baring in on Clarke, only to drag his shot wide.
Craddock almost opened the scoring 20 minutes from time with a fierce rising drive which Lillis just tipped over.
The stalemate was broken in the 78th minute, when Grant got in down the left and crossed for Donnelly to head home.
Within four minutes the hosts made sure of the victory, when Donnelly returned the favour to set up a tap-in for Grant as United were caught out pushing for an equaliser.
It was tough to take for the visitors, who deserved at least a point.