Sean O'Driscoll admitted he was "stunned" by the decision to send Dexter Blackstock off as his Nottingham Forest side lost 1-0 to Derby in a bad-tempered East Midlands derby.
Just 32 seconds into the second half referee Robert Madley made the game-changing decision to dismiss Blackstock for an apparent elbow on Rams captain Richard Keogh.
The visitors made their numerical advantage count with Craig Bryson scoring the only goal of the game as Derby notched their third straight win over their great rivals, the first time they have put together such a sequence in 100 years.
While O'Driscoll stopped short of criticising Madley, he questioned his decision to give Blackstock his marching orders for what appeared an innocuous aerial challenge, particularly after more severe incidents went unpunished in the first half.
O'Driscoll said: "It came so quickly and there are aerial challenges all the time in the English game so I didn't know what it was for. That's the difficulty, when you don't know what it's for.
"But, watching it on the replay, then I suppose you can see, to give the referee the benefit of the doubt, you can see why he gave it. But in the context of the game I just think it's a harsh one, very harsh.
"They're not easy games to referee. In the context of the game I thought he took everybody by surprise. I don't think there was a great deal of shouts from the Derby players or even our players. We were in stunned silence.
"I just thought something might have been said at half-time, I spoke to the referee and said 'was anything said at half-time that we are going to clamp down on the first thing we see' and, to be fair, they said that wasn't the case, he's done it on his merits.
"We'll have to look at it - see if we can get it rescinded."
If O'Driscoll was perplexed at the contest's turning point, Derby first-team coach John Metgod attempted to offer some logic to Madley's controversial call.
"I'm in the lucky position to go home and in about two-to-three hours' time, I'll have another look at it and make up my mind, which for the referee, obviously he can't," he said.
"The only thing I would say is I can't see a referee taking a decision like that if he's not absolutely convinced. If there was any doubt whatsoever, I can't see him sending him off."
There has now been a player sent off in each of the previous four encounters between these two and Metgod pointed to last year's contest, when the Rams won 2-1 despite playing almost the entire game with a man less, as proof that their task was not necessarily easier once Blackstock had taken an early bath.
"You would have expected that to be pivotal as well because that was the first minute," he added.
"As much as it can be pivotal, you've still got to do it. Our experience last season has shown that there is more pressure on the 11."