Loanee Ivan Toney powered home a firm header just before the half hour mark and that proved to be the game’s only goal, with Scunthorpe collecting another crucial three points.
Evidently pleased to register the away success, Alexander expressed his delight post-match.
He told The Iron PlayerHD: “At this stage of the season it’s about picking up points and winning games, and I thought the performance today showed what it takes to win.
“We played exceptionally well, controlled the game, had lots of possession and we’ve scored the winning goal.
“It shows the intelligence of the players, the motivation of the players and the fitness so I’m delighted with every single one of them because it’s a fantastic three points.
“They’ve (MK Dons) got lots of good players and they play a way that can cause a lot of problems but I thought we nullified that threat in the important areas and the discipline showed from the players.
“They stayed compact, killed the spaces and we never went chasing.
“We got the goal at a good stage of the game and apart from the odd occasion, I thought we were superb today.”
Striker Toney’s goal was his fourth in Iron colours and arrived following a precise Josh Morris corner kick – his 14th third tier assist of the campaign.
Full of praise for both players, Alexander also highlighted the importance of keeping a second clean sheet in succession and Joe Anyon’s performance.
“It was a fantastic header and we know the quality that Josh possesses from set pieces and general play,” he continued.
“Ivan has bullied the defender and powered it in so I’m delighted for him. He’s got four goals and he and Paddy (Madden) put in a great shift for the team today.
“I’m delighted for Joe too as it has been a difficult season for him. He’s not played a lot because of the form of Luke (Daniels) and he has needed an opportunity like this.
“He trains well, has got a great attitude and that’s why he’s ready to come in and play as well as he has.
“The stats show that we’re such an attacking team and we want to take the game to the opposition but our lack of clean sheets has been costing us.
“So today I’m delighted for the players, they’ve worked extremely hard and their motivation is fantastic.”
It’s a quick turnaround for United, with an Easter Monday clash against Chesterfield next on the horizon at Glanford Park.
Keen to heap praise on the away support, Alexander hopes for more of the same performance-wise in Scunthorpe’s remaining League One fixtures and also issued an update on injured midfielder Matt Crooks.
He added: “The fans were brilliant. We could hear them all game through.
“As a club performance today it was fantastic and I’m delighted for them because they’ve travelled a lot of miles this season. It was important that we gave something back to them.
“They’ve kept their faith and hopefully we can repay that in a bigger way in the long run.
“We have to go into the next game determined to win the match and what I’ve seen recently is two winning performances with different styles and we might have to find a different style on Monday.
“We have to make sure we go into that game determined to get a result. We’re after results at this stage of the season and Monday is our next opportunity to do that.
“Matt unfortunately is going to miss the rest of the season. He has picked up a knee injury and will be out for 10-12 weeks which is a blow for us because he’s been fantastic.
“We’re gutted for Crooksy but he’s coming to the game on Monday so he’s still got a part to play with the other players. We’re just gutted it has ended as it has.”
See much more from Graham Alexander and Ivan Toney on The Iron PlayerHD.