Ethan Robson’s 72nd-minute goal was the difference between the two sides as Danny Cowley’s side came up short at Stadium MK.
The defeat follows the 1-0 reverse at the hands of Wigan two weeks ago – and comes just days after a 5-3 loss at the hands of Wimbledon in the Papa John’s Trophy.
The result sees Pompey drop to 12th in the table.
And just as worrying will be Pompey’s lack of goals, with their blank against the Dons their third in a row in the division.
That statistic was at the forefront of many fans’ concerns as they took to Twitter to express their views.
Here’s what they have been saying after the 1-0 loss...
@GavH_: I can’t see how we’re going to get promoted on this showing, so called better players and better management but same old #Pompey.
@PORTSMOUTHFCLEE: I’m not going to press the panic button just yet. But every game seems very disjointed…. Thought we were poor again today #pompey
@Shovell96: We talk about not getting a striker in, but forget Cowley brought in 2. Hirst and Ahadme, neither made the squad today. Poor recruitment there imo. Still no creativity. No goal in 3 games, 1 point from the last 9. Cowley has to improve this. #Pompey
@Lawro77: Disappointing once again from #pompey. Short of goals, it needs to be sorted.
@Steve_Wrixon: We still have no link between forwards and the rest of the team.
We can play all day and we won’t score. Still not creating anything.
We have 3 centre mids just trying to fit them all in. I would rather lose after battering someone then a game like this! #Pompey.
@harfynn: I think the Cowleys talk a good game, nice guys but really don't know what they are doing any more than Jackett. Trying to draw 0-0 every week isn't the answer. #Pompey
@McgrealDeclan: Front three can’t start the next game, Harness can’t carry on ghosting games.
@FookingEll: Wonder why Ahadme couldn't make the bench today, especially with the attacking options we have at our disposal.
Understand he has hardly set the league alight but he can't be any worse than Marquis.
@TheChief657: Didn’t take our chances, poor in possession and naive when defending. Not a good day at the office #Pompey