Karl Robinson admits he still feels hard done by from the last time MK Dons and Peterborough met ahead of their clash on Saturday.
Saturday sees the first meeting between the two clubs since May 2011 when Posh edged a thrilling League One play-off semi-final 4-3 on aggregate.
According to Robinson that whole tie turned on a controversial red card for Dons midfielder Stephen Gleeson late in the first leg which allowed Grant McCann to score from the penalty spot and bring Peterborough, who had earlier had Charlie Lee sent off, back to 3-2 on the night.
Gleeson's red card was overturned and he played in the second leg but was unable to prevent the Dons losing 2-0 and Posh went on to secure promotion to the Championship in the final at Old Trafford where they beat Huddersfield - who 12 months later would inflict more semi-final misery on the Milton Keynes club.
Robinson reckons his players were still angered by Gleeson's sending off going into the second game at London Road and the emotion remains raw for the 33-year-old.
"I'm still angry," he told Press Association Sport. "I'm still bitter because I feel we were cheated out of the tie, cheated out of a place in the play-off final and cheated out of the chance to get this club promoted into the Championship.
"The referee (Jonathan Moss) evened it up with 10 minutes to go, simple as that. It was embarrassing. And now he is in the Premier League.
"We should have been going to London Road with a two-goal cushion, maybe even better than that if it had been kept at 11 against 10, but we went there bitter - even though we had won the first leg. We went there angry, and I don't think we even turned up that day. It affected us, no doubt about it."
The Dons, unbeaten in Sky Bet League One so far this season, return to London Road on Saturday for the first time since that defeat and Robinson has revenge on his mind.
He added: "It is unfinished business. We go there, into the lion's den, fearless. I have a very good side, one of the best during my time here."