Rangers manager Steven Gerrard claimed Livingston should have gone down to 10 men after Joe Aribo went off with a head wound that required 20 stitches.
Aribo bled heavily on the pitch after being caught by Ricki Lamie's elbow midway through the first half of Rangers' 1-0 Betfred Cup win at the Tony Macaroni Arena.
Gerrard, whose team face Hearts in the semi-finals, said: "He's had 20 stitches, he got a real nasty gash which has gone right through.
"You could see on the pitch, it was gushing with blood. The doctor stitched him up and did a fantastic job. He will certainly be out for the weekend.
"I don't think Lamie has meant to do him, he's not that type of player, but in my opinion it was serious foul play."
Gerrard made a conscious effort to hold back his thoughts when pressed on Livingston's approach, especially after learning that home boss Gary Holt felt Filip Helander should have been sent off for bringing down Lyndon Dykes.
"It could have gone either way but it's pretty interesting him saying we got away with one," Gerrard said.
"There were a (couple of head knocks) and there were a couple the last time we played this team as well.
"A boy has just gone off with 20 stitches in his head. I've watched Lamie long enough to know he's not that type of player. I'm not accusing him of anything out of order but that's serious foul play because he has led with his elbow."
Rangers were given plenty of uncomfortable moments after Glen Kamara's deflected strike gave them the lead in the fifth minute, although they had decent control of the final 20 minutes.
Gerrard said: "It was a performance full of courage and desire, it was a very brave performance but it wasn't pretty on the eye.
"It's difficult here because you are bombarded with aerial balls and long throw-ins and it's a game of fighting for the first ball and second ball."
On Helander's challenge, Holt had said: "It didn't help us but I don't think it cost us the game. We still created enough chances.
"You do want the fine lines and wee breaks to go your way against the bigger teams. It didn't go our way but it is one of those things.
"I think the referee (Don Robertson) said he had a look and said it was a red card after the game. He's apologised to the players and sometimes you have to accept he is man enough to do that. I think he said to the players walking off.
"But attacking and defending we need to be better. We need to get in and score those chances we are creating. You put in all that effort but at the end we are out of the cup.
"It's a Catch 22 because I thought to a man they were excellent. I can't fault their effort and desire, it is about that belief to go on and do it."
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