MK Dons 0-1 Scunthorpe
Karl Hawley's goal means League One Scunthorpe go into the last day of the season with a chance of survival.
MK Dons had more of the first-half play with the Iron content to counter-attack and they scored in just that fashion.
Hawley poked home Jimmy Ryan's low cross before the hosts pressed hard for an equaliser, forcing goalkeeper Sam Slocombe into a trio of fine saves.
Scunthorpe held firm to move within three points of fifth-bottom Colchester with a game to go.
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MK Dons manager Karl Robinson told BBC Three Counties Radio:
"It's a reality check for a lot of people. I've said to them that it's the first time they're wearing the kit and it'll be the last time some of them wear it, because that's unacceptable. The energy and enthusiasm wasn't there for 45 minutes.
"Second half we were alright. We completely dominated the game and probably should have got back on level terms, but the first half has let us all down I think.
"There's been times over the course of MK Dons history where maybe the fans haven't been as vocal or as passionate as what they've been over the last two months. They've shown that in abundance today and we've shown a complete lack of that in the first 45 minutes.
"For me today, we've let them down today. I said that to the players and the ones that have a problem with that are the ones I don't want at the football club."
Scunthorpe United manager Brian Laws talking to BBC Radio Humberside:
"It's got to be classed as an important win for us for sure. The fact that it takes us to the last game of the season with some hope.
"It's goal difference that will be a key and we will probably have to score a couple more goals and hopefully Colchester lose their game.
"We are still in with a shout, we've still got a little bit of fight left in us and hopefully we can get a huge crowd behind us on Saturday against Swindon.
"Great credit to the players because coming in to this game it was another must win but it was one that if we don't approach it in the right manner you could get heavily criticised and heavily defeated here. "