Dons led 2-0 after 13 minutes thanks to Alex Gilbey and Joe Mason goals, but Dan Barlaser and a Freddie Ladapo brace saw the Millers leave Stadium MK with all three points. Here's how the Dons rated on a disappointing afternoon.
1. Lee Nicholls - 7
Not a lot to do in the opening half, but picked it out of his net three times in the second. A mix-up with Cargill cost one goal, but went the right way at the penalty again.
2. Dean Lewington - 6
Had some swagger in the first half as Dons ran riot, but like the rest of the defence, came off the boil in the second.
3. Baily Cargill - 4.5
His best performance for a long time in the first half, but seemed to go to pieces as Rotherham turned up the wick. Gave away the penalty, and earned a daft sending off in stoppage time will cost him three games.
4. Joe Walsh - 6.5
Looked Dons' best defender until late in the day when the backline let in three cheap goals.