A late brace from substitute Michael Higdon sent Sheffield United into the quarter finals of the Capital One Cup.
Higdon, introduced when United were trailing 1-0 thanks to Benik Afobe’s second-half penalty, scored twice late on to turn the clash on its head.
The striker nodded in with minutes left to cancel out former Sheffield Wednesday loanee Afobe’s second-half opener.
And in stoppage time, Higdon drilled a low finish home to put United ahead.
After a quiet first half, Stefan Scougall and Marc McNulty both went close early in the second half while Dons’ Dean Bowditch tested Mark Howard in the United goal.
But Howard was finally beaten from the penalty spot by Afobe, after Craig Alcock felled Dele Alli.
Both League One sides made a lively start to this cup tie, but neither could break the deadlock in the first half.
Afobe, the former Arsenal man, twice went close to putting the home side ahead, but United goalkeeper Mark Howard foiled him.
Then Liverpool target Alli went down on the edge of the box, but referee Roger East waved away the protests.
United boss Nigel Clough made five changes to his side to face MK Dons, with McNulty, Louis Reed, Harrison McGahey and Jay McEveley returning to his starting eleven - with Terry Kennedy and Connor Dimao both featuring on the bench. Ben Davies was also recalled for the meeting with Kark Robinson’s side, who dispatched the visitors’ namesakes from Manchester in the earlier rounds.
Out went the suspended Chris Basham, on-loan Paddy McCarthy, James Wallace, Jose Baxter and Jamal Campbell-Ryce.
MK DONS: Martin, Lewington, Flanagan, McFadzean, Potter, Bowditch, Reeves, Spence, Alli, Carruthers, Afobe. Not used: McLoughlin, Kay, Grigg, Baker, Randall, Powell, Hitchcock.
SHEFFIELD UNITED: Howard, Alcock, Harris, Doyle, Murphy, Scougall, McNulty, Davies, McGahey, McEveley, Reed. Not used: Turner, Baxter, McGinn, Campbell-Ryce, Higdon, Kennedy, Dimaio.
REFEREE: Roger East (Wiltshire),