The Dons picked up a magnificent three points on the road thanks to a 1-0 win at promotion hopefuls Derby County.
The game also saw the Dons collect their ninth clean sheet of the campaign and end a tough week with a hugely-impressive five points.
Darren Potter and Nicky Maynard returned to the starting XI for the fixture at the iPro Stadium as the Dons looked to pick up a third positive result of the week.
The Dons settled well and limited to their hosts to a couple of crosses into the box which were comfortably dealt with, while a Craig Bryson free-kick ended up on the roof of the net.
George Baldock, starting his third successive game, was offering an outlet from right-back but, after a purposeful run, his cross over-hit as the midway point of the first half approached.
Like for most games this season, the Dons were more than matching their opponents and a Rob Hall free-kick almost caught out former England keeper Scott Carson on 24 minutes.
The Rams then enjoyed a good spell of pressure up until the half-hour mark, which included Bradley Johnson firing over after Thomas Ince had mis-kicked Cyrus Christie’s cross.
However, their best chance of the afternoon came on 34 minutes but Jason Shackell glanced Ince’s free-kick wide of the target when well placed.
Karl Robinson’s men hit back on the counter attack but, after receiving the ball from Samir Carruthers, Hall curled his effort past the far post.
David Martin made his first save on 44 minutes, getting strong hands behind a 25-yard shot from Jeff Hendrick which appeared to move in the air.
Martin followed that up with a smart stop in injury-time, pushing away Chris Martin’s fierce shot after turning on the edge of the box.
The Dons were dealt a blow at the start of the second half when Carruthers was booked, his 10th of the season – he will now miss the games with Bristol City and Huddersfield.
Johnson headed into the side-netting before Martin comfortably gathered a weak effort from his namesake, Chris - the Rams’ tails were up.
But the Dons rallied and got a foothold back in the game 10 minutes into the second half, with the hosts’ next opportunity not arriving until the hour mark when Ince fired wide from 25 yards.
The men from MK1 were continuing to deal with what Derby had to throw at them while, at the other end, they broke and Darren Potter was almost found inside the 18-yard box.
With 20 minutes remaining, a superb touch from Carruthers freed Murphy, who was cynically brought down by Hendrick – the former saw a shot blocked from the resulting free-kick.
The introduction of Alex Revell had certainly made a difference and he was inches away from picking out fellow substitute Dean Bowditch on 77 minutes, but Bradley Johnson got back to cut out the pass.
The Dons were growing in confidence and both Potter and Joe Walsh saw close-range efforts blocked as the game entered the final 10 minutes.
And that pressure was rewarded on 82 minutes when Forster-Caskey beat Carson in some style, finding the net from 20 yards – his first goal for the Club.
As expected, Derby enjoyed more of the ball as the game ticked towards the 90th minute – their best chance falling to Ince, who volleyed wide at the back post when well placed.
Substitute Andreas Weimann then headed wide from eight yards before Martin comfortably dealt with a long-range strike from Ince in the first minute of injury-time.
MK Dons: Martin; Baldock, McFadzean, Walsh, Lewington (c); Potter, Forster-Caskey; Murphy, Carruthers (Bowditch 76), Hall; Maynard (Revell 59).
Unused subs: Cropper, Spence, Powell, Williams, Emmanuel-Thomas.
Bookings: Maynard, Carruthers.
Goals: Forster-Caskey (82).
Attendance: 30,075, (811 Dons fans).