Daryl Powell believed Oliver Holmes should not have been sent off in Castleford’s defeat to Leeds.
The Tigers lost 28-24 to the Challenge Cup winners despite playing 50 minutes with 12-men.
Holmes was sent-off following an incident with Richie Myler, where he appeared to kick the fullback.
The forward had been struck by Myler while the pair were wrestling, leading to Holmes’ retaliation.
“I think it’s poor discipline from Oggy,” Powell said.
“I’m not sure I’d have sent him off, it might have been ten minutes, it’s poor discipline but if effected the game so hugely it has to be something significant to send someone off.
“I’ll have another look back at it but I don’t think it was a sending off and Rich Agar said the same as well.”
Despite that, Powell was delighted with his side’s effort.
“I thought we were awesome today, we didn’t play great in the first half and got a player sent off and that was always going to make life difficult but second half we played really well, we’ve got 12 men and opened them up on both edges and better execution we score more points.
“Defensively, it’s hard to play rugby league a man down, the way the game is played with numbers defensively makes it tough but we scrambled and worked our backsides off for each other. So I thought there were loads of positive signs in there.
“Today showed the spirit is unbroken and was a massively positively sign.”