Hibernian were "let down" by refereeing decisions said manager Paul Heckingbottom after he was sent to the stand during a 1-1 draw with Celtic.
Kristoffer Ajer's own goal gave Hibs the lead, but Ryan Christie levelled after Celtic were awarded a free-kick which Heckingbottom disagreed with.
The Hibs boss kicked a water bottle which hit an assistant referee, leading to him being red carded.
"It was a bad mistake from me," said Heckingbottom.
"The bottle was just there in front of me. I think I kicked an advertising board before Glenn Middleton's decision. I shouldn't have done it but I was sent off for confronting the fourth official.
"I have no need to see [referee] Kevin Clancy. Maybe he'll watch it back and I'll get a call from him apologising.
"We were anything but a soft touch today. They should be proud of that performance. The tactics mean nothing unless you play with fire in your belly."
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Both managers agreed Celtic midfielder Olivier Ntcham was fortunate to escape a red card after pushing Hibs' Josh Vela in the face.
"Kevin Clancy's not made any decisions on purpose, but we as a football club have been let down," Heckingbottom told BBC Scotland.
"There's a free-kick we should've had but didn't get, Glenn Middleton went through and Moritz Bauer falls over and trips him and slips, but they get the free-kick. It comes straight back again, we put a good press on and pinch the ball back and they get the free kick five seconds later. The players thought it was a drop-ball, not a free-kick.
"It's poor from our part, but decisions go wrong and we have to deal with it, but the [non] sending off is the most frustrating thing for me.
"We should've been playing against ten men. For Ntcham's sending off, 100%."
Lennon 'doesn't understand' penalty decisions
While Celtic manager Neil Lennon agreed his man could have seen red, he also felt his side could have had several penalties.
"You can't raise your hands but maybe common sense was used by the referee," said Lennon. "We'll need to have a quiet word with Olivier about that. So, possibly [he could have been sent off].
"I'm not going to criticise the players. We dominated the game away from home. We're not going to win every game.
"They're not debateable penalty decisions, they're clear-cut penalty decisions. And if we get those it changes the psychology of the game completely. I don't understand how at least one of them was given."