Mark Hughes believes Ryan Nelsen's dismissal against Aston Villa left Blackburn with no hope of a recovery.
Rovers were already trailing Martin O'Neill's side courtesy of John Carew's opener when Ryan Nelsen hauled back Gabriel Agbonlahor in the penalty area.
Hughes admits Phil Dowd was right to award a spot-kick, but in also sending off Nelsen the referee killed off any chance of getting something from the game.
Gareth Barry dispatched the penalty with late goals from Ashley Young and Marlon Harewood securing a 4-0 win for Villa.
When asked was he aggrieved at the result, Hughes told Sky Sports: "Yeah to say the least.
"We've lost 4-0, but no way was there a four-goal difference between the sides.
"The turning point was the penalty. It was a penalty, but I don't know why he sent him off. We had people back there.
"Once he sent Ryan off that was the end of the game."
Not only did Blackburn have a first half effort from Benni McCarthy harshly ruled out for offside, but Hughes felt Villa's late efforts should not have stood.
"I also felt we had a decent shout for a goal that was chalked off," he continued. "For the first 30 minutes we were excellent.
"Their fourth goal was a very marginal goal. They got the benefit of the doubt.
"In fairness the last two goals were offside anyway, 2-0, 4-0, it doesn't make a difference,
"I've calmed down now. I've got to try and curb it."