Match ends, Colchester United 1, Rochdale 4.
Rochdale moved into the play-off places as Colchester United slumped to a fifth successive League One defeat.
Dale's Matthew Lund pounced to open the scoring after Michael Rose's free-kick was parried by Sam Walker.
Peter Vincenti added a second after Walker again failed to hold a shot, and Ian Henderson made it three from spot after Kaspars Gorkss tripped Stephen Dawson in the box.
Gavin Massey pulled one back before Jack O'Connell headed home a fourth.
Henderson twice went close to adding a second of his own, hitting the crossbar in each half.
Colchester slip to 23rd place in the table, five points from safety, while Rochdale move past Oldham Athletic into the top six following their 4-0 home loss against Yeovil Town.
Rochdale manager Keith Hill told BBC Radio Manchester:
"I've got a very good squad of players and I'm happy with the result and majority of the performance.
"I think at times there's too much pressure on each of us - I mean there's an expectancy on us to come here and win.
"We're not a League One football club, Colchester are as they've been here for how many seasons?
"I think this result and this performance reflects what we're capable of doing as a squad."
- 41HewittSubstituted forClohessyat 45'minutes
- 6EastmondBooked at 30mins
- 7Sanchez WattSubstituted forBonneat 53'minutes
- 19HealeySubstituted forMasseyat 45'minutesBooked at 90mins
- 8LundBooked at 3minsSubstituted forHeryat 84'minutes
- 7VincentiBooked at 34minsSubstituted forAndrewat 75'minutes
- Charles Breakspear
- Shots on Target
Second Half ends, Colchester United 1, Rochdale 4.
Ian Henderson (Rochdale) hits the bar with a right footed shot from very close range following a corner.
Corner, Rochdale. Conceded by Sam Walker.
Attempt saved. Michael Rose (Rochdale) left footed shot from the centre of the box is saved in the bottom left corner.
Gavin Massey (Colchester United) is shown the yellow card.
Foul by Gavin Massey (Colchester United).
Stephen Dawson (Rochdale) wins a free kick in the defensive half.
Corner, Colchester United. Conceded by Ashley Eastham.
Corner, Colchester United. Conceded by Jack O'Connell.
George Moncur (Colchester United) wins a free kick in the defensive half.
Foul by Bastien Héry (Rochdale).
Attempt saved. Freddie Sears (Colchester United) right footed shot from the right side of the box is saved in the centre of the goal.
Corner, Rochdale. Conceded by Tom Eastman.
Substitution, Rochdale. Bastien Héry replaces Matthew Lund.
Attempt saved. David Fox (Colchester United) right footed shot from outside the box is saved in the centre of the goal.
Hand ball by Matthew Lund (Rochdale).
Attempt missed. Matt Done (Rochdale) left footed shot from the left side of the box misses to the left.
Foul by David Fox (Colchester United).
Calvin Andrew (Rochdale) wins a free kick in the defensive half.