Notts County manager Shaun Derry admitted his dissapointment with Ronan Murray's red card in the Magpies' loss to Peterborough United, which brought their recent winning run to an end.
The Irish midfielder was sent off after 15 minutes of a seven-goal thriller with Peterborough at London Road for throwing a punch at Danny Swanson.
By then Enoch Showunmi, with a rasping fourth-minute finish from an Alan Sheehan delivery, and Murray, who swept in a Kieran Freeman cross in the seventh minute, had fired the in-form visitors into a two-goal lead.
But their hopes of a fourth successive win were eventually dashed as Posh - spearheaded by the first hat-trick of back-in-favour frontman Nicky Ajose's career - made the most of their man advantage.
Ajose halved their arrears on the half-hour with a fine low finish from Mark Little's cut-back before top-scorer Britt Assombalonga headed them level nine minutes into the second period with his 21st goal of the season after meeting Nathaniel Knight-Percival's cross.
Ajose completed the turnaround with 16 minutes to go with a spectacular 25-yard rocket but County stunned the home faithful as Jack Grealish drilled in a leveller from an acute angle two minutes later.
But Ajose spared Posh's blushes when pouncing on a rebound in the 85th minute after Knight-Percival's header from a Swanson corner had been brilliantly saved by unfortunate County keeper Bartosz Bialkowski.
Derry said: "We arrived with a gameplan and we were executing it perfectly for the first 15 minutes until we had Ronan sent off.
"It is a case of pressing the self-destruct button of the highest order and it has absolutely killed us.
"Ronan is not the kind of guy you expect that from and it has completely baffled me.
"That aside I was delighted with the way my players went about the game.
"It used to wind me up when I heard managers say they were determined to take the positives out of defeats but I know what they mean now."
Posh boss Darren Ferguson was determined to concentrate on the positives of a come-from-behind success.
He said: "We won the game and that's all that matters at the moment.
"The confidence and belief is coming back after a couple of victories.
"The players showed tremendous character to come back from being behind. In fact it was like the good old days of seeing us turn a game around shooting towards the home end.
"I'm really pleased for Nicky because he has been very unlucky during his time here.
"I made my mind up to give him a run of games when I brought him back in from his loan spell at Swindon and he is getting the goals."