Goals from Callum Camps and Ian Henderson saw MK Dons beaten 2-0 by Rochdale at the Crown Oil Arena.
Camps struck from a corner after just two minutes while Henderson headed in from a set-piece on the hour to seal the victory for the home side.
The defeat leaves the Dons 19th in the Sky Bet League Two table, heading into their trip to Fleetwood Town at the weekend.
Boss Paul Tisdale made three changes to the side which drew with Coventry City at the weekend. In came Baily Cargill, Jordan Bowery and Brennan Dickenson who replaced Joe Walsh, Jordan Houghton and Hiram Boateng.
His side started brightly and sent an early cross into the box which goalkeeper Jay Lynch saw out of play.
However, Rochdale took the lead with their first attack two minutes later, as Camps was left unmarked from a corner, allowing him to fire a first-time right-footed shot past Lee Nicholls. 1-0.
Jordan Bowery went close to responding on eight minutes but his header from Callum Brittain’s cross flew just over the bar. Rochdale almost picked off the Dons on the counter soon after, but Matty Done failed to keep his left-footed shot down.
On the quarter-hour mark, Callum Brittain sent a first-time effort into the side netting after connecting with George Williams’ low cross. At the other end, Rhys Norrington-Davies fired wide from another threatening Dale corner.
Soon after, Norrington-Davies struck wide of the upright for a second time. Aaron Morley then curled off target direct from a free-kick, as the home side maintained their dominant start to the contest.
The Dons, though, almost found an equaliser with 28 minutes gone as a ball from the left fell kindly for Brittain on the right side of the box. His first-time volley beat Lynch but was cleared off the line by a Dale defender.
Tisdale’s side had the post to thank for keeping the deficit at one with eight minutes to play in the half – it was MJ Williams who saw his fierce strike crash against the crossbar before Camps’ follow-up effort was blocked by Jordan Moore-Taylor.
Brittain went just as close on 43 minutes as he lifted a shot just over the crossbar after being teed up, 15 yards out. That was the Dons’ final chance to restore parity before the break.
The Dons emerged from the break with Ben Reeves on in place of Bowery. It was the home side, however, who went closest early on in the half, with Moore-Taylor forced into a last-ditch block to deny Norrington-Davies.
Tisdale and his men responded, with Baily Cargill delivering a superb ball across to the far post. Brittain latched onto the cross but could only find the side netting. Kieran Agard was then brought on for Kasumu.
Shortly before the hour mark, Williams dispossessed Done at the crucial moment inside the MK Dons penalty area. It did, though, lead to a chance for Morley, whose dipping curler was tipped over by Nicholls.
Rochdale then won a corner from which they doubled their lead. Morley’s delivery was met inside the six-yard area by Henderson, who had the simpe task of heading into the bottom corner. 2-0.
The Dons responded with both Cargill and McGrandles trying their luck from the edge of the area – the latter saw his low drive saved by Lynch.
McGrandles had another attempt on 69 minutes but had this one blocked. Rathbone then fired wide for hosts, before substitute Fabio Tavares wasted a golden opportunity for the hosts to extend their lead.
With 12 minutes to play, Agard met a cross from Brittain but headed wide. Brittain threatened again in the final two minutes of regulation, but couldn’t keep his volley down.
MK Dons: Nicholls, Williams, Lewington, Cargill, Gilbey, Bowery (Reeves 46), Dickenson (Boateng 62), Moore-Taylor, McGrandles, Brittain, Kasumu (Agard 54)
Unused subs: Moore, Poole, Martin, Houghton
Booked: Gilbey, Boateng
Rochdale: Lynch, Worrington-Davies, O’Connell, Williams (Wilbraham 75), Camps, Keohane, Rathbone, McShane, Done (Tavares 65), Morley, Henderson (c) (Andrew 81)
Unused subs: Wade, Ryan, Bradley, Matheson
Goal: Camps (2), Henderson (60)
Referee: R Lewis
Attendance: 2,286 (128 away)