Lee Gregory's stoppage-time penalty gave Millwall a deserved three points in a 2-1 victory over MK Dons on Saturday afternoon at The Den.
Gregory gave The Lions the lead midway through the first-half, but Ben Reeves equalised six minutes later.
Gregory, however, had the last laugh as he converted his spot-kick in injury-time.
Neil Harris made one change to the starting line-up which defeated Peterborough United on Tuesday night, with Aiden O'Brien replacing Harry Smith in attack.
In a welcome boost, meanwhile, Steve Morison and Jed Wallace both returned from injury to take their place on the substitutes' bench.
The first chance of the game fell to The Lions, but Byron Webster could not direct his header on goal from Shaun Williams' corner.
On 24 minutes, The Lions took the lead. Gregory appeared to have been brought down inside the penalty area, but referee Ross Joyce waved the appeals away. However, that would work to Millwall's advantage as, following Shane Ferguson's cross, Gregory was on hand to head home from six yards out for his 13th goal of the season.
MK Dons nearly got themselves level just three minutes later following good work down the right-hand side, but Kieran Agard was just unable to poke the ball past Tom King, instead winning a corner-kick.
From the resulting corner, The Lions were to concede their first goal in over 14 hours of football. O'Brien's clearance found its way to Reeves on the edge of the box and the midfielder's well-struck effort bounced past King and into the Millwall goal.
Ex-Lion Ed Upson attempted to haunt his former employers as the second-half got underway, but his low shot lacked enough power to trouble King.
Morison made a welcome return to action on 55 minutes as he replaced Fred Onyedinma. The striker had a golden opportunity to score with his first touch, but he shot wide from 12-yards out,
Morison was involved once more with 69 minutes on the clock, seeing a goal-bound header deflected over the crossbar for a corner.
MK Dons broke away following a Millwall corner-kick with 79 minutes gone, but excellent defending from substitute Wallace ensured that the score-sheet was kept level.
It seemed as though Webster would power home the winning goal from Gregory's inviting cross with 83 minutes on the clock, but the ball was agonisingly flicked away from the defender as he stooped to head.
At the other end, Dean Bowditch could have snatched all three points for the visitors, but he somehow headed over Nicky Maynard's cross from just a few yards out.
As the clock ticked into injury-time, The Lions won their fourth penalty in three games as Gregory was brought down inside the penalty area.
The striker dusted himself down and stepped up to take the spot-kick, placing it low to the right of Martin to give The Lions the advantage once more.
A frantic five further minutes of stoppage-time followed, but there was no further action in front of goal.
The Lions are now 17 matches unbeaten and remain in the League One Play-Off places.
Millwall: King, Cummings, Craig, Williams, Thompson (Butcher, 87'), Gregory, Onyedinma (Morison, 55'), Webster, Ferguson (Wallace, 72'), O'Brien, Cooper. Subs not used: Girling, Hutchinson, Worrall, Romeo.
Bookings: Ferguson, Thompson, Gregory, Morison
Scorers: Gregory (24', 90+1' (pen))
Milton Keynes Dons: Martin, Baldock, Lewington, Walsh, Upson, Potter, Reeves (Maynard, 74'), Williams, Agard (Barnes, 58'), Muirhead (Bowditch, 84'), Downing. Subs not used: Nicholls, Ngombo, O'Keefe, Tilney.
Bookings: Walsh, Martin, Lewington, Baldock
Scorer: Reeves (30')
Referee: Ross Joyce