Neil Warnock admitted Omar Bogle cost Cardiff City the game against Bristol City after the striker's red card gifted the hosts the chance to claim three points at Ashton Gate.
The Bluebirds boss also raged against referee Mike Jones, who he called 'inconsistent' after the failure to show Bristol City's Marlon Pack a second yellow.
And while Warnock had no complaints about Bogle's red card, he wasn't afraid to accept the striker let down his teammates despite scoring an equalising goal.
Bogle slotted a first half leveller before seeing red in the Bluebirds' 2-1 defeat to rivals Bristol City.
Warnock was less than impressed with his striker, saying: "He should have got a foul in front of the dugout but two wrongs don't make a right. You've got to be better than that in a derby match.
"I can't say anything good about Bogle because that's cost us the game. If you want me to say anything good about his performance, it's a waste of time.
"Why play well and score and then go and get sent off? Cost your team the game. As a manager you need 11 players on the pitch but that changed the whole context of the game and gave them a massive lift.
"He's got a three game ban now, that serves him right."
Warnock also directed his post-match fury at referee Jones, who he believed was inconsistent throughout.
There were a number of flash points throughout the game that the referee got wrong, according to Warnock.
"We've got a Premiership referee, and he's a good referee, who I expect to be consistent," said Warnock on the official.
"Sometimes they come into the Championship and they don't want to be here.
"And today I didn't think he was consistent.
"I thought the booking on Peltier, in the first two or three minutes, was very very minimal. I thought the worst tackle all game was Pack on Bamba, over the top. I could have sworn he was going to book him and Pack should have been off, 48 minutes, should have been 10 men.
"I've got no complaints whatsoever on the red card. But we didn't get many 50-50s today.
"I thought he was doing well as well, Omar. But it means I couldn't put Tomlin on earlier than I did because we were outnumbered."
Bogle, for his part, took quickly to Twitter to apologise.
He'd previously looked impressive before taking an early bath, but wrote: "Sorry to everyone, killed the team.
"Tackling not in my nature and its shown in the tackle. Thanks to the supporters. I'll make it up to you."
