Substitute Mark Carrington scored a dramatic winner deep into stoppage time as MK Dons secured a hard-earned three points against ten-man Dagenham.
The Warrington-born midfielder, only introduced nine minutes from time, saw his speculative shot escape the grasp of Daggers keeper Tony Roberts to keep Karl Robinson's men firmly in the League 1 play-off race.
Dagenham had looked set to survive the second-half dismissal of winger Danny Green, who was shown a straight red card for an elbow on Luke Chadwick, and take a point that would have aided their fight to escape the relegation zone.
But Roberts' mistake three minutes into added time gifted the Dons' only their third win on the road this season, at the start of a crucial spell of four consecutive away trips.
Victory may have come at a cost - Carrington brought on to replace the returning Sam Baldock, who pulled up lame just 15 minutes after coming off the bench himself.
But it was the perfect way to start a sequence of fixtures that could have a significant impact on the Dons' season, particularly if they can continue to improve on their travelling record.
Carrington fires the winner deep into stoppage time.
Robinson's policy of putting faith in young players was in action again as he opted to start 19-year-old full-back Adam Chicksen
in place of the sidelined Gary MacKenzie.
That meant a move inside for skipper Dean Lewington, who was charged with the supervision of the rangy Marvin Morgan - a particularly dangerous weapon in conditions far from suited to passing football.
Morgan was a handful in the early stages, chasing balls over the top with great enthusiasm and looking to seize on mistakes from defenders facing their own goal.
On 12 minutes, he managed to bundle Lewington out of possession just outside the box, but his cross aimed for Gavin Tomlin was expertly cut out by Mathias Kouo-Doumbé.
Kouo-Doumbé would be on the receiving end of Morgan's bustling style just before the half-hour, this time the big Daggers striker able to breach the box from the left, but he was denied by the advancing David Martin.
Luke Chadwick competes with Romain Vincelot.
It was hardly easy on the eye as the Dons' usual passing game was reduced to low-risk football by a pitch that threatened to defy every pass played. Though they tried to string moves together when space was afforded them, Dagenham's energy rarely allowed it.
Dagenham continued to look the greater threat in the first period and were on the front foot again three minutes before the break - Morgan and Green combining to set up Romain Vincelot on the right, but his shot was blocked by Lewington.
If the first half had been Dagenham's, the Dons began the second with clear intentions to wrestle back the initiative. Robinson switched to a 4-3-3, allowing Stephen Gleeson space to get on the ball in midfield, and the chances started to flow.
Danny Woodards drives forward down the right.
Just two minutes after the break, Peter Leven clipped a lovely pass out to the right flank, Daniel Powell got beyond his marker Femi Ilesanmi and his final pass was just behind Chadwick 12 yards out.
It kicked off a good spell for the visitors, who put together the best move of the game ten minutes later. Chicksen, growing in attacking influence, set off on a positive charge down the left before Lewis Guy and Chadwick combined to set up Leven, whose 25-yarder whistled past the post.
Leven was looking for a penalty four minutes later, convinced Mark Arber had dragged him to ground when well-placed in the box, but referee Craig Pawson did not oblige.
Dagenham threatened to find some momentum when Abu Ogogo got in behind Chicksen down the right on 70 minutes, but Kouo-Doumbé's recovering challenge was both powerful and immaculately timed.
Jabo Ibehre races with Dagenham skipper Mark Arber.
It was a sign that the hosts were not out of it, but their chances were dealt a blow four minutes later when Green, having been booked for a poor challenge on Chicksen in the first half, got his marching orders.
Frustrated after striking a usefully-positioned free-kick straight at Chadwick's one-man wall, the Daggers winger jumped for the subsequent ball with a dangerously raised arm. Chadwick hit the deck, and Green was shown a straight red card.
To their credit, the home side continued to battle manfully, resisting the temptation to drop deep.
Lewis Guy holds off Dagenham's Peter Gain.
But the Dons could sense a huge opportunity to seize the points and were somehow kept out on 79 minutes when a goalmouth scramble saw Chadwick, Ibehre and substitute Rowan Vine were all denied at close-range.
The loss of Baldock, so hampered by injury this season, was a potential blow, but it was his replacement Carrington that proved the hero in dramatic circumstances.
With Dons shirts flooding forward in search of a winner, the former Crewe man moved positively with Kouo-Doumbé's pass before pulling the trigger from 25 yards and Roberts did the rest.
Dagenham &amp; Redbridge (4-4-2): Roberts; Ogogo, Doe, Arber, Ilesanmi; Green, Vincelot, Gain, Elito (Nurse 70); Tomlin, Morgan.
Subs not used: Lewington, Antwi, Damian Scannell, Bas Savage, Darren Currie, Billy Bingham.
MK Dons (4-2-3-1): Martin; Woodards, Kouo-Doumbé, Lewington, Chicksen; Gleeson, Leven; Powell (S. Baldock 66 (Carrington 81)), Guy (Vine 66), Chadwick; Ibehre.
Subs not used: Searle, Stirling, O'Hanlon, G. Baldock.
Goals: Carrington 93
Booked: Woodards, Ibehre
Referee: Craig Pawson (South Yorkshire)