Motherwell manager Stephen Robinson told Curtis Main he had let the club down after the striker was sent off in the 1-0 defeat to Kilmarnock.
Robinson saw three of his centre-backs taken to hospital during the Ladbrokes Premiership game before Main's two bookings in quick succession dented the hosts' hopes of responding to Jordan Jones' first-half strike.
Robinson felt Jones' winner was a "mis-hit cross" and did not use the injuries to Charles Dunne, Carl McHugh and Christian Mbulu as an excuse.
Dunne and McHugh clashed heads in the 11th minute and substitute Mbulu was replaced in the 28th minute after going off with an eye problem.
But Main angered his manager in the 71st minute when he fouled Stephen O'Donnell with a flailing arm before pushing the Killie right-back in the face. Referee Steven McLean showed him a yellow card for each offence.
Robinson said: "Curtis Main let us down completely, I'm really cross about his lack of discipline. He probably should have been sent off for his first offence so I've absolutely no complaints about the decision."
On the injuries, Robinson said: "Losing three boys in the space of five minutes was something I've never experienced before but they say you never stop learning in management.
"I have to give credit to the boys who were on the pitch because they gave me absolutely everything.
"Richard Tait went to centre-back and it was one of the best performances I've seen from a Motherwell player. That's proper desire. He was top class. He won more headers than anyone else on the pitch.
"Of course we're not happy about losing the game – and we lost it to a mis-hit cross.
"There was nothing in the game. Did we create enough? Maybe not but we were brave and we tried to move the ball about."
Robinson faces a challenging team selection for Saturday's Lanarkshire derby at Hamilton. As well as the defensive problems, striker Ryan Bowman was absent after the club received a bid from an unnamed team.
Robinson said: "Christian Mbulu potentially has a detached retina while the other two boys are concussed – and Carl has a history of that, of course.
"Peter Hartley's out with a calf problem and I've no idea whether he'll be able to make it for Saturday. We may have an offer for Ryan Bowman, it came in very late in the day so we felt it was in everyone's best interests that he wasn't involved."
Jones disputed Robinson's assessment of his goal after his ball from the left flank sailed into the far corner, but Killie boss Steve Clarke did not care.
"Jordan said he saw the keeper a little bit off his line and curled it to the back post," Clarke said.
"Jordan will tell you it was a shot but it doesn't really matter whether it was a shot or a cross, it was a good delivery into the box and it's gone in the back of the net and got us three points.
"The only disappointment for me was that we didn't capitalise on the chances that we created second half. We should have made it a much more comfortable afternoon for the old manager sitting on the bench."
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