Manager Ally McCoist warned Gregg Wylde he must learn from his mistakes after the youngster was sent off in Rangers' 3-1 win over Dundee United at Ibrox.
Two goals from striker Nikica Jelavic and an own-goal from Garry Kenneth extended Rangers' lead at the top of the Scottish Premier League table.
On the downside for Rangers were Jon Daly's goal and the late dismissal of Wylde for a kick at Willo Flood.
McCoist said: "He will have to learn things like that are not acceptable."
And the Ibrox boss added: "I haven't seen it but I'm told that he kicked out at somebody. Ten years ago we wouldn't be talking about it, it would be nothing.
"Nowadays it's a sending off and that's not in Gregg's defence, far from it. He should know better."
Rangers are 12 points clear of Motherwell, and 15 ahead of Celtic, who meet at Fir Park tomorrow.
The Steelmen, however, have a game in hand over Rangers, while Neil Lennon's men have two.
"The most pleasing thing was the win and the three points were vital to us," said the Rangers manager.
"We got the game we thought we would get, it was really tough.
"In terms of the performance, we can do miles better with and without the ball. But it's a great result because Dundee United can put you under pressure and they certainly did that."
Lee Wallace hobbled off with a thigh problem but McCoist hopes the injury is not too serious with the defender set to join up with the Scotland squad for next week's friendly in Cyprus.
McCoist said: "I haven't had a chance to speak to him but I know he is in a bit of pain and he's on the treatment table and iced up at the moment.
"I'm hoping it's just a whack rather than anything else. He is in a bit of pain and discomfort at the moment so I don't know how that will leave him in terms of the international set-up for next week."
Kyle Lafferty was absent from the squad today and McCoist added: "He got hit in training yesterday in a clash with Matt McKay and got a dead-leg. He got a whack and was ruled out today."