Dons conceded three goals inside half-an-hour, leaving them with a mountain to climb. Despite goals from Troy Parrott and Scott Twine, they were unable to overcome the 3-0 deficit, denting their automatic promotion credentials.
Here's how we rated the players at Stadium MK.
1. Jamie Cumming - 6
A rare mistake allowed Wednesday to take the lead as he spilled Berahino's effort on 10 minutes. Was beaten three times in quick succession but had a quiet second period.
2. Harry Darling - 6.5
Spoke openly afterwards of his disappointment at how Dons defended early on as they conceded three for the first time since October.
3. Warren O'Hora - 6.5
Recovered well from the terrible start Dons made, limiting Wednesday to precious little in the second half
4. Dean Lewington - 6
His innocuous header dropping to Bannan to score from 35-yards was pure bad luck for the skipper. Otherwise, looked assured.