Jack Ross did not believe Max Power should have been sent off and has confirmed Sunderland will appeal the decision.
The 25-year-old will be banned for the next five games, though the visit of Notts County in the Checkatrade Trophy means it will effectively be six.
Power saw red in the 23rd minute of the 2-2 draw with Walsall, shown a straight red for a late tackle on Liam Kinsella after losing control of the ball.
It is Power’s third red card in eight League starts this season.
Ross gave a passionate defence of Power in his post-match press conference following the League One draw at the Banks's Stadium.
"It is not a sending off," said Ross.
"This season I try and be fairly measured with all my comments, even with officials, at times we have had some decisions go against us.
"If you take Max in isolation, I think your gut tells you at the time - having been experienced in playing and coaching - and against Oxford I could see why it was given, Bradford is an easier one. Today, my gut reaction at the time is that it isn't even a yellow card.
"I have had the benefit of watching it back, it isn't even a yellow card.
"If it isn't overturned, I would be amazed.
"It is a huge decision to make at that time of the game and it is not a red card, you can't put up an argument for it being a red card.
"It is hugely frustrating, we were very good in that opening period of the game, I don't want to be disrespectful and say we would have definitely won the game but in the opening period we were very good and it had an impact on the rest of the game, as we know."
When pressed on whether Sunderland will appeal the decision, Ross added: "Without a shadow of doubt.
"If I had no TV replays I would appeal it, I knew at the time it wasn't a red. I have watched it and it isn't even close. That is only my opinion, other people's opinion that matter on it.
"I asked the ref at half-time and he said for serious foul play. Naturally, I disagreed with that. I didn't speak to him at full-time. I try and keep myself and emotions in check.
"I was hugely frustrated with large aspects of the performance today."
Ross revealed the midfielder apologised to Ross in the Sunderland dressing room but the Scot insists he has nothing to apologise for.
Ross said: "He is apologetic to me but it is ridiculous for him to be apologetic as he doesn't even give the referee a decision to make, he doesn't commit properly, it is nothing.
"He is concerned as we know the ramifications if it doesn't get overturned and it has a huge bearing on our season as well.
"Lets not take this in anyway related to the other red cards, in isolation today, it is the wrong decision."