Rangers chief executive Patrick Stewart speaks with referee chief Willie Collum over Auston Trusty decision

Rangers chief executive Patrick Stewart has spoken to Scottish FA head of referees Willie Collum to seek an explanation over a key decision in the Premier Sports Cup semi-final, STV can reveal.

Celtic went through to next month’s final against St Mirren with a 3-1 extra-time win after what was an incident-packed match.

Johnny Kenny had put Celtic in front at Hampden before Rangers were reduced to ten men following Thelo Aasgaard’s challenge on Anthony Ralston.

However, Rangers believed Celtic should also have had a man sent off just before half-time when Auston Trusty’s boot made contact with goalkeeper Jack Butland’s head when the Englishman had both hands on the ball.

Match referee Nick Walsh decided there wasn’t force behind the contact and showed the USA international defender a yellow card but some Rangers players were furious it wasn’t red. VAR officials backed the on-field referee and didn’t ask him to revisit his decision on the monitor.

Rangers chief Stewart has sought an explanation over the decision, which was one of several flashpoints in a match where extra-time goals from Callum McGregor and Callum Osmand settled the contest in Celtic’s favour.

The decision is likely to be explained publicly by Collum in his monthly VAR Review Show, which is expected to be broadcast in the next week.

Speaking at full-time, Rangers captain James Tavernier had expressed his disbelief that no red card was shown to Trusty.

“With Thelo, the ref said it’s the force of how he’s gone into the challenge. You know, he’s not really seen Ralston come for the ball. He’s just gone for the ball.

“But then Jack’s diving on the floor, he’s already got the ball and he gets kicked in the head.

“No matter what the intent is, it’s still intent and you can’t kick a goalkeeper in the head.

“So you’d expect the same level of approach. And then obviously further into the game, Dio [Mohamed Diomande] gets kicked in the stomach area just where you’d say the same place and nothing’s done.

“But that’s no excuses. We have to as a team be more clinical in that game.

“It’s disappointing, but you know, it’s up to us to react to them moments. You know, things are going to get thrown at us, nothing’s always going to go your way. So, it’s down to us to react.

“I thought we reacted quite well, but it’s just the small margins in these big games – it’s the details you have to be really good at.”

As a result of Sunday’s match, the SPFL has announced that Rangers’ Premiership match against Hibernian has been moved to a Monday night and will be played at 7.45pm on December 15 due to the Premier Sports Cup final the previous day.