Livid Cardiff City boss Dave Jones was critical of Stephen McPhail after the Bluebirds captain was sent off in the 51st minute of the derby clash with Swansea City at the Liberty Stadium.
It is the second time McPhail has been sent off at Swansea this season and was particularly galling for Jones as the second yellow card was for petulantly booting the ball away.
"A lack of discipline from Stephen has probably cost me three points," said the Bluebirds boss after the 2-1 draw.
"When we took the lead we were playing the better football and in charge of the game. It looked like Swansea would have to send more players forward and we might have then picked them off.
"It wasn't about the occasion, it was more frustration, but you can't kick the ball away.
"It's a lack of discipline on Stephen's part. He doesn't normally do it and probably thought he was a little bit hard done by over a few free-kicks that weren't given.
"The frustration boiled over in the end. That's what the atmosphere can do to you. We were in control at that point and that's the disappointing thing. He cost us the win and he's got to accept it.
"He'll be more disappointed than everyone else. He knows he let us down - but it happens. Stephen isn't the first person to do it and he won't be the last. You just hope he learns from it."