Wes Thomas’ first-half header proved the difference as MK Dons were beaten 1-0 by a resilient Grimsby Town sid at Blundell Park.
Thomas headed in a cross 27 minutes in to give the hosts a lead which they managed to hold on to despite going down to 10 men late in the first half.
Chuks Aneke and debutant David Wheeler went closest to salvaging a result for Paul Tisdale’s men, who will look to end a run of three straight defeats on Tuesday evening when they take on Oldham Athletic at Stadium MK.
Boss Tisdale handed Russell Martin and Wheeler their MK Dons debuts as two of four changes made to the starting XI. Martin replaced Joe Walsh in the centre of the defence while Wheeler came in to the side in place of Peter Pawlett. The other two changes saw Ryan Watson slot in at right midfield for Conor McGrandles and Aneke make way for Osman Sow.
MK Dons started well but it was Grimsby who made the first breakthrough on goal, three minutes in. The hosts won possession inside the Dons half and released Thomas. His shot was saved - not that a goal would have stood, with the flag raised for offside.
Jordan Cook then tried his luck from distance but the effort was gathered comfortably by Nicholls before Watson registered the Dons’ first shot on goal - a low, left-footed curler which skipped just wide of Sam Russell’s post.
On 13 minutes, Gilbey threatened with a driving run through the centre of the pitch but he was dispossessed on the edge of the area by Ludvig Ohman. At the other end of the field, Jordan Moore-Taylor got himself in the way of Elliott Embleton’s strike on goal.
The Mariners drove forward again in the 22nd minute but Martin did brilliantly inside his own penalty area to win the ball off Cook as he looked to pull the trigger.
While one debutant was impressing in defence, Wheeler went close to marking his first 25 minutes as a Dons player with a goal but, from Baily Cargill’s cross, he couldn’t direct his header on target.
Three minutes later, Wes Thomas found himself in a similar position to Wheeler at the opposite end of the pitch and the Mariners striker was able to convert with his header to give the hosts a lead. 1-0.
MK Dons went in search of an immediate response and forced a corner on the near side. Lewington’s cross was flicked into the mix by Wheeler but Grimsby were able to clear.
Shortly after, Houghton won possession in the centre of the park and then found Sow, who wasn’t allowed to turn on the edge of the box.
Tisdale’s side were dealt a further blow with 10 minutes remaining in the half as Jordan Moore-Taylor was forced off with an injury. The centre-back tried to run the ailment off following an earlier knock but conceded defeat and was replaced by Walsh.
They were, though, then handed a boost by referee Paul Marsden, who reduced the hosts to 10 men in the 40th minute. Harry Davis was the man dismissed for the hosts for dragging down Agard, who was through on goal - a clear goalscoring opportunity denied.
The foul itself presented Lewington with an opportunity to mark his 700th MK Dons appearance with a goal, however he sent his free-kick over the crossbar from 20-yards out.
In the final minute of the first half, Sow created a shooting opportunity from a deep ball into the box. The Swede brought the cross down on his chest and then fired a shot on goal on the turn, only for a deflected to lift it over.
The Dons weren’t able to threaten from the resulting corner and headed into the dressing rooms at the break behind by one.
Tisdale’s side returned to the field unchanged but eager to get back on level terms.
They almost found the equaliser within a minute of the re-start but Sow’s effort was blocked on its way to goal. MK Dons recycled the ball and Gilbey flashed a right-footed shot wide from the edge of the D.
An overlapping run from Martin on 49 minutes presented the debutant with a chance to cross into the mix which he did. His ball fell to Agard, whose fierce strike was blocked by a defender.
The chances kept coming for Tisdale’s side as Gilbey saw a deflected attempt spin wide. Wheeler was then denied a shot on goal from Houghton’s through ball courtesy of an excellent tackle from a Mariners defender. The tackle led to a Dons corner from which Agard sent an acrobatic effort wide of the target.
It was a great response from the visitors, who thought they were about to level things in the 55th minute when Wheeler headed into the path of Agard - he, though, was denied by the linesman’s offside flag.
In the 63rd minute, Cargill fired over following a tricky run through the Grimsby midfield. Tisdale then used the stoppage to bring Aneke on from the bench in place of Sow.
The momentum stayed in the Dons’ favour and on 68 minutes Watson raced into the area only to see his low cross cleared away by the Grimsby defence.
Tisdale’s final roll of the dice came in the 69th minute with Ryan Harley introduced in place of Agard.
A minute after the change, his side went agonisingly close to drawing level but Russell did brilliantly to save at the feet of Gilbey, who had connected with Watson’s cross.
They went even closer with 17 minutes to play from another Watson delivery. Aneke met the ball this time but couldn’t direct his header on target from close range.
Two minutes later, Wheeler came within a whisker of meeting Gilbey’s low cross and levelling the scores. Gilbey did brilliantly in the build-up, driving down the left, but couldn’t quite connect with his new teammate.
The Dons were then denied what appeared to be warranted penalty shouts after Watson was brought down inside the box. Ref Paul Marsden looked to be considering the call but eventually waved play on.
Grimsby had spent the majority of the second half camped inside their own half but they had a chance to settle the tie on the counter attack with three minutes remaining. Thomas raced through onto a long ball but was denied by a diving save from Nicholls.
MK Dons won the ball back from the resulting corner and forced one of their own. Aneke met the delivery from Lewington but his looping header landed wide of the goal.
Five minutes of added time were awarded and in the first of those, the Dons won another corner. Watson’s ball made it all the way through to Gilbey, at the back post but his attempt rose harmlessly over the bar.
The Mariners then had another opportunity to end the drama but Nicholls acrobatically denied them a second goal.
After regaining possession, the Dons threw men forward and Houghton saw a shot blocked. Two corners followed but the ball ended up in the arms of Russell.
Moments later the whistle blew, leaving the Dons sixth in the Sky Bet League Two table.
Starting XI: Nicholls; Martin, Moore-Taylor (Walsh 38), Cargill; Watson, Houghton, Gilbey, Lewington (c); Wheeler, Agard (Harley 69), Sow (Aneke 64).
Unused subs: Moore, Baudry, McGrandles, D’Ath.
Booked: Gilbey, Cargill
Attendance: 3,862 (141 away)
Referee: P Marsden