The game shot to life in the 83rd minute as Wallace was sent-off by referee Darren Handley for an off-the-ball incident with Jonny Williams. This came after Fernando Forestieri was booked for an alleged dive on the edge of the MK Dons box.
Before this, Wednesday had hit the frame of the goal three times. On the stroke of half-time, Daniel Pudil’s cross-cum-shot rebounded off the far post. Substitute Atdhe Nuhiu then headed against the woodwork from a Forestieri free-kick and Pudil was unlucky as his stabbed 70th-minute effort looped onto the bar.
Late on, Wednesday’s penalty claims were dismissed by the referee as Forestieri went down in the box.
Coach Lee Bullen, who was standing in for the absent Carvalhal in the post-match press conference, said: “It’s been a very frustrating evening. The first-half performance was tough, you have to give credit to Karl Robinson’s team, they were fighting for their lives. We couldn’t find any rhythm in the game.
“The second-half performance was full of energy, full of drive. We did everything but put the ball in the net.
“Carlos is a little bit frustrated at the moment, its been a very emotional night. Some of the decisions went against us.
“What does Fernando (Forestieri) have to do, just stand there and get kicked? It wasn’t a yellow card. He’s paying for a reputation. It’s getting frustrating because he’s an honest lad.
“It was a late change in referee, it’s a stage of the season where we need as strong a ref as possible. It’s a tough one to be thrown into at this stage.”
Pudil had the first chance of the game, striking a volley wide of debutant goalkeeper Charlie Burns’ right-hand post from the edge of the box.
The visitors responded and, after some lapse defending from Jack Hunt, defender Jordan Spence found himself through on goal but Wednesday keeper Kieren Westwood parried away his weak shot with ease.
In the 23rd minute, Wallace tested the keeper from 25 yards and, just minutes later, a mix-up between Dean Lewington and Darren Potter almost led to a comical own goal.
Wallace should have done better in the 29th minute after good approach play by Alex Lopez but his shot from inside the box was easily saved by Burns.
Then, in the 32nd minute, Barry Bannan spurned the best opportunity of the half, lifting the ball over the bar from inside the box after a drilled cross from the left-hand side by Pudil.
Pudil was again involved on the stroke of half-time as his curling effort struck the frame of the goal with Burns well beaten.
Wednesday started the second half better and Pudil was involved again, flashing the ball across the six-yard box after a neat reverse pass by Fernando Forestieri.
In the 50th minute, a whipped cross from the left-hand side by Pudil was headed over the bar from close range by substitute Atdhe Nuhiu.
Nuhiu came even closer five minutes later as he headed against the post from a Forestieri free-kick and, in the 58th minute, he headed over a Wallace cross with the goal gaping.
Wednesday continued to attack and in the 60th minute, Glenn Loovens headed a Wallace corner wide of the goal.
Forestieri then twisted and turned inside the box before forcing a reaction save from Burns at his near post.
Great footwork by Nuhiu in the 65th minute set Forestieri on his way to goal but again 19-year-old Burns was equal to the shot at his near post.
Pudil was a constant threat and his cross in the 69th minute fell into the path of Nuhiu, but he was unable to finish as MK Dons threw bodies in the way of the ball.
Pudil then hit the bar with a stabbed effort from Wallace’s in-swinging corner.
In the 75th minute, Forestieri teed himself up for a half-volley on the edge of the box but his effort went just wide of the post.
Tempers flared in the 83rd minute as Wallace was given a straight red card by referee Darren Handley for an off-the-ball incident with Jonny Williams.
In stoppage time, Wednesday hit the frame of the goal for the fourth time in the game as Bannan’s free-kick cannoned off the bar.