Cardiff City were the victims of a "huge mistake" by referee David Coote in Friday's defeat at Birmingham, according to manager Russell Slade.
Matt Connolly was penalised for a handball inside the area in first-half stoppage time but television replays clearly showed the ball hit his face.
Paul Caddis scored from the spot to give Birmingham their first home win in two months.
"The referee's awarded a decision that's beyond belief," said Slade.
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"He had a fantastic view of it and it's clearly hit Connolly's head. It's a huge mistake and hopefully he's big enough to put his hands up."
Coote was a late replacement to take charge at St Andrew's on Friday, and Slade had to be restrained at half-time as he attempted to confront the official as he headed for the dressing rooms.
Connolly was not showed a yellow or red card by Coote after blocking James Vaughan's goal-bound effort inside the six-yard box following goalkeeper David Marshall's fumble.
According to Slade, that suggested Coote realised he had wrongly awarded a penalty.
"I accept we make mistakes but he's 12 yards away and there's nobody in his way," he said. "I don't think we can be getting those things wrong."
Wasted chances and Morrison's injury
Cardiff created plenty of opportunities to equalise in the second half, with Sammy Ameobi wasting the best opening when well placed inside the area.
Scott Malone was then denied by a stunning last-minute save by home goalkeeper Tomasz Kuszczak.
"If I'm going to be ultra critical, we need to just finish things off," Slade added. "Whether it's a shot or a final decision on a ball - it let us down slightly.
"But on another day we could have scored three or four easily.
"We controlled large parts of the game. which is encouraging for an away team. The better side lost for sure."
Cardiff lost defender Sean Morrison to a knee injury after only nine minutes, and Slade fears the 24-year-old could be out for up to a month.
His injury gave Bruno Ecuele Manga his first taste of action since September after recovering from a groin injury.
Slade will wait to discover the full extent of Morrison's problem before deciding whether or not to recall Ben Turner from his loan spell with Coventry City.