Cardiff City manager Neil Warnock felt Bristol City should have had a player sent-off before his striker Omar Bogle saw red in the 2-1 Championship defeat.
Bogle was dismissed on 55 minutes after earlier equalising for Cardiff.
Warnock had no complaints about the red card but felt referee Mike Jones should already have sent off Marlon Pack.
"The worst tackle of the game against Sol Bamber should have been a cert [second] yellow against Pack and he has ignored it completely," said Warnock.
"I haven't got a clue why he hasn't booked him... he should have been off. They knew he should have been off.
"That really upset me today."
Cardiff paid a high price when Aden Flint headed in the winner from a corner to inflict a third defeat of the season on the Bluebirds.
Warnock said his team were distraught "as they should be" after losing a Severn-side derby he believed they controlled before the red card.
"I felt we were the better side and felt we dominated the game," added Warnock.
"But these things sometimes go against you and that's the way it's gone today.
"They should have a man off on 48 minutes and we've ended up 10 men clambering away and it's disappointing.
"I know it's only 48 minutes and he (Jones) doesn't want to send anyone off then, but that's the rules of the game.
"He shouldn't be above that, the referee, the ref is there to referee the game."
The result leaves Cardiff third in the Championship as they go into the international break - a position Warnock is happy with despite dropping out of the top two.
"It's a long season - and if you'd have said at the start of the season we'd be in the top two middle of November I'd have thought you were smoking something really," he said.
He also played down concerns after Nathaniel Mendez-Laing limped off early in the first half.
"It was a precaution - his thigh tightened up very much. It was a major blow to us that really because we missed him," Warnock added.