Dons survived a late barrage from Lincoln City to claim victory against the league leaders in an enthralling 2-1 win at Stadium MK.
Callum Brittain scored after just two minutes, tapping home Kieran Agard's cross before Tyler Walker equalised 10 minutes later for the visitors. George Williams then scored a bizarre second on 22 minutes as Jordan Bowery's strike deflected off the floored defender, with cries for offside turned away.
Lincoln looked to turn the screw in the second period, but came within the width of the crossbar of drawing level at the death when Jason Shackell's header thumped the woodwork.
The result sees Dons climb to tenth in the table, while Lincoln are toppled from the top by Blackpool.
After the 3-2 defeat at Wycombe on Saturday, Paul Tisdale made two changes to the side, dropping Conor McGrandles, who missed a second penalty in as many games, and captain Dean Lewington. They were replaced by Ryan Harley and Callum Brittain, and it paid off within 90 seconds.
Jordan Bowery, who scored his first goal for Dons on Saturday, nodded a high ball down into the path of Kieran Agard, who broke in behind the Lincoln defence to pull back for Brittain to slide in the opener.
The League Two champions had taken to League One in style, winning all three of their opening games. Despite falling behind early, the Imps played with a high attacking line and flowed forwards with confidence. Jack Payne was causing Dons a lot of issues with his movement in the centre of the park from the opening whistle, so it was of little surprise when he was heavily involved in Lincoln's equaliser on 11 minutes. Some swift two-touch passing unlocked Dons' defence, with Payne laying it off to Tyler Walker, who carefully picked out the bottom corner of Lee Nicholls' net.
Dons did not break stride though, and matched fire with fire. Brittain had covered almost every blade of grass in the opening 20 minutes, while Hiram Boateng showed excellent feet in the centre of the park to carve space for those around him.
Despite some of the great football being played though, Dons retook the lead in somewhat bizarre circumstances midway through the first half. Rising high above Neal Eardly, George Williams nodded into the path of Bowery, but the striker's shot was blocked, bounced into the floored Williams and past keeper Josh Vickers.
With the wind in their sails, Dons should have doubled their advantage two minutes later when Kieran Agard's tenacity paid off as he shared a 1-2 with Baily Cargill, but fired just wide of the mark.
As the game flowed from end-to-end, Lincoln should have equalised for a second time 11 minutes before the interval when Jordan Houghton dallied on the ball on the edge of the box, gifting Payne with a sight of goal. His chip though was poor, and swiped away at the second attempt by Nicholls.
The second half continued just as the first ended. Lincoln looked excellent in possession as they sought an equaliser though it was Dons who had the better chances, with Hiram Boateng and Ryan Harley both having a sight of goal.
As the half wore on though, Lincoln began to tighten the screw. Dons changes, introducing Alex Gilbey and Conor McGradles in the centre of the park, did little to stem the side as the Imps poured forwards, hemming the home side into their penalty area for long periods as they looked for an opening.
And it almost came with the final action of the game when Jason Shackell - the man who scored just as late in the reverse fixture at Sincil Bank - saw his header thump the crossbar as Dons held on to claim all three points.
Referee: Michael Salisbury
Attendance: 8,166 (1,350)
MK Dons: Nicholls, Cargill, Martin, Poole,Williams, Brittain, Houghton (McGrandles 62), Boateng (Lewington 81), Harley (Gilbey 62), Bowery, Agard
Subs not used: Moore, Healey, Nombe, Kasumu
Lincoln City: Vickers, Toffolo, O'Connor (Andrade 66), Shackell, Payne, Bostwick, Walker (Akinde 66), Grant, Morrell, Eardley, Anderson
Subs not used: Smith, Bolger, Chapman, Bradley, Lewis