David Prutton made himself an instant hero with the home support as the U's consolidated their place in the top six - and closed the gap on second place - on Tuesday night.
A goal in each half was enough for the U's tenth home win of the season as they beat the Dons by a 2-0 scoreline
With Leeds and Charlton both losing during this week, the U's closed the gap on the automatic spots to eight points with a game in hand.
The U's could afford to miss a penalty at the start of the second half as they eased to victory against a visiting side reduced to ten men for much of the second half.
And, after the horror of twelve goals conceded in two games at the start of 2010, two successive clean sheets will have restored much confidence in the U's defence.
Aidy Boothroyd made just one change to the side that drew with Gillingham on Saturday, bringing in Kevin Lisbie in place of Kayode Odejayi.
New signing David Prutton made it onto the substitutes bench, whilst Christian Ribeiro made his home debut.
However, Paul Reid missed out after picking up an injury in training - Matt Heath taking his place in defence.
The first seven minutes of the game passed without too much incident, although Dons loanee Randall found his way into the book for a foul on Tierney as the U's man clipped the ball down the touchline.
The visitors were the first to have a chance of note as a through ball found Wilbraham, who set himself twenty yards out and drilled in a low shot that Williams dived full length to make sure that it was going the right side of the post from a U's perspective.
The U's were seeing plenty of the ball in the final third on the left flank, with Tierney's throws giving the Dons plenty to think about.
And it was from one of those throws that the U's took the lead on 18 minutes.
Gueret had made a clear decision early on to come and claim all of those balls, but he spilt the ball under pressure from Platt, who knocked the ball back to Lisbie. With one telling thrust of his right boot, the ball flashed into the back of the net.
The Dons keeper, usually so unflappable, then spilt again with Heath in close attendance, dropped a free kick in from Wordsworth. Again it dropped into the danger area, but this time he was able to fall on the ball and collect.
The U's almost then got in again as they turned the screw. Lisbie chased down a ball from Tierney and, as Woodards tried to see it out, the home striker robbed it from his toes.
He darted in from the byline but, by the time he faced Gueret, he still had a narrow angle to contend with and couldn't force his shot past the keeper.
Lisbie had been enlivened by his goal and almost beat the Dons defence with a flick on from Wordsworth, but McCracken stood firm to see the ball back to his keeper.
The Dons were still in the game at one down, though, and had a shot deflected over the bar by some brave U's defending midway through the half.
Gleeson followed Randall into the book for a deliberate handball on the halfway line just as Lisbie looked like he might wriggle free on the counter.
From a U's free kick not long afterwards, O'Toole's flick on landed at feet of Woodards, who got his feet tangled up and had to eventually hack clear from inside the six yard box after indecision with his keeper.
Doumbe did much better when Lisbie was put through into the area, closing down the U's man just as it looked like he was about to pull the trigger eight yards from goal.
The Dons came back into the game somewhat as the half entered the final fifteen minutes, but they still looked nervous at the back as the U's pushed forward.
One Dons move five minutes before half time almost got the visitors in, but the U's hacked clear and sixty seconds later almost had Lisbie bursting in on goal before McCracken got a timely boot in.
The U's positive first half came to a worrying close, however, as Ribeiro limped off injured. He was replaced by John White who returned to his familiar right back berth.
As expected, the Dons started brightly at the start of the second half, and put together a move shortly after the interval that ended with Randall driving a shot down Williams' throat.
The U's did well to resist that early pressure, and thought they had doubled their advantage as Wordsworth's free kick wrongfooted Gueret and looked like it had crept in.
Instead it had been deflected behind for a corner and when Platt flicked on at the near post, the U's claimed for a handball, for which the referee waved away all appeals.
They did get their penalty shortly afterwards as Lisbie was pulled to the ground as the U's flicked a free kick into the danger area.
Half time substitute Stirling was the man who tugged him to the ground and saw red for his offence, but shortly after trudging off, he turned around to see Gueret pull off a fantastic save from Lisbie's penalty.
Lewington followed him into the book for verbal dissent not long afterwards, and the U's needed to capitalise on their opponents frustrations.
Instead, the Dons rallied and were playing the ball to Wilbraham in the heart of the area, looking to pick up the pieces.
But Lisbie went close on 58 minutes, picking up a ball on the edge of the box and curling the ball just past the post with Gueret flat footed.
As the Dons looked to force a way back into the game, they introduced the ever dangerous Puncheon for Randall for the final half an hour of the match.
The U's followed with a change of their own not long afterwards, introducing Prutton for his debut in place of Ifil.
And the Leeds man's first contribution was to help the U's to a two goal advantage. He had won the ball earlier in the move and then picked it up about thirty yards out, skipping past a man before lashing a superb shot into the top corner.
The Dons responded in kind by introducing Baldock for Chadwick for the final quarter of the game. He had scored twice in the same fixture last season and the Dons would need more of the same this time around.
Townsend sent over a dangerous cross on 71 minutes, but no one got across to the ball as it went across the six yard box.
With fifteen to go, Prutton went into the book for kicking the ball away, before the Dons almost gave themselves hope as Baldock crashed one against the post with Williams relieved to see it go to safety.
Lisbie headed over the bar with nine minutes to go and hurt his back as he fell, and was later replaced by Gillespie for the final stages.
The Dons also had one flicked onto the roof of the net, but the dying stages of the game passed without too much incident as the U's grabbed another important home win.