Sheffield United boss Chris Wilder says Mason Holgate apologised to teammates after their 5-0 home thumping by Brighton.
Holgate saw red on 13 minutes for a high challenge on Kaoru Mitoma.
Wilder said afterwards: "He has apologised to the boys, he understands it and he is an experienced pro.
"He has got it wrong. I want us to be competitive, I want us to win tackles, we can't have a passive game.
"It is a competitive game, it is not a non-contact game but we have to get that right, Mason has to get that right. It is huge setback for us in the approach to the overall game.
"I am torn, I am a competitor and I understand that it was a very, very strong challenge and the game has moved on."
