Single goal enough to separate sides.
The U’s were unchanged, and they started brightly with Massey having a shot deflected just over the bar for an early set piece.
But the U's were unable to build up a true head of steam in this one and, despite their improvement from the first game, were again left to rue defeat.
In a game short of many clear cut chances, keeper Sam Walker was otherwise untroubled, whilst Gavin Massey forced a fine save out of Ian McLoughlin early in the second half.
The Dons had swept the U's aside earlier in the season in a 6-0 win at their home ground, but this time it was just Delle Alli's goal that separated the two sides across the ninety minutes.
MK Dons completed the double over Colchester United on Tuesday night - but this time it was a much closer affair.
But the Dons were quickly into their stride with plenty of early possession, with the U’s having to see away a couple of set pieces in those first ten minutes.
At the other end, Porter wriggled away from his centre half and turned towards goal, striking a fierce left footed shot that forced a good save out of McLoughlin.
Hewitt then opened his legs to show his pace down the right and deliver a dangerous low cross that was cleared, before Fox also had a foray into the box that was well blocked.
Massey was lively in the early stages, and sent over a cross on 16 minutes that looked like it might find Hewitt, but McLoughlin fended the ball away at the far post.
The U’s could not afford to rest on their laurels though and the Dons were a threat throughout from set pieces.
From one such effort on 20 minutes, Spence rose the highest to nod inches over the crossbar.
Delle Alli, who had moved to Tottenham in the January transfer window, had had a quiet first half hour, but had his first sight of goal just before that mark arrived. He dragged his shot from 25 yards well wide though.
Shortly afterwards, a far post header from Briggs met the hand of Lewington at close range but, despite appeals from the home fans, the referee showed no interest in the appeal.
The U’s were giving as good as they got, though, and more good build-up play on 34 minutes saw Clohessy send over a dangerous cross that just eluded Porter, who appeared to have been nudged just in time.
Lapslie was booked not long before half time for a crunching tackle on Alli, but the midfielder picked himself up to give the visitors the lead on 43 minutes.
A free kick was half cleared by the U’s but was hooked back into the danger area, where Alli broke through to slot home.
The U’s could feel hard done by, after largely protecting Walker, but were still well in the game at the halfway mark.
The home side made a change at half time, with Fox being replaced by Gilbey for his first appearance of the year.
It was Massey who was the next to go close though, forcing a fine full length save out of McLoughlin with a brilliant volley from the edge of the box.
The U’s made their second change on 63 minutes as Moncur returned to action in place of Lapslie, whilst Alli was replaced by Reeves.
It was the first of a tough double at home this week, next up is Bristol City as the U's look for a way to shake off their home troubles and escape the bottom four.
Centre halves McFadzean and Kay ensured that balls to the front were sent back from whence they came and, despite a couple of late corners, the U's were unable to beat McLoughlin.
The home side, faced by eight men behind the ball, kept looking for a way to unlock the door, but came up against a wall able to repel them throughout that second period.
The visitors were happy to soak up pressure and let the U’s play in front of them, and chances were at a premium in the second half.