Scott Brown claimed referee Willie Collum crumbled under a “pressure decision” when he did not send off Fabio Silva in Rangers’ 2-0 win over cinch Championship side Ayr at Ibrox.

The Portuguese forward had been booked in the first half of the Scottish Gas Scottish Cup last-16 tie where the home side took the lead after 10 minutes through a Borna Barisic strike which deflected in off Roy Syla, when he tackled George Granger after the break.

Collum resisted the temptation to flash a second yellow before he soon cautioned Brown for complaining – and then Silva, on loan from Wolves, netted the second after 76 minutes to take the Light Blues into the quarter-final draw.

Gers boss Philippe Clement had on Friday backed Collum despite Rangers reportedly asking the Scottish Football Association not to appoint the official to any of their games going forward after his part as the VAR official in a contentious non-penalty decision which went against them in their Old Firm derby defeat at the end of the year.

It was Collum’s first involvement with Rangers since and former Celtic captain Brown was unimpressed.

The Somerset Park boss said: “The second goal comes from a man who probably shouldn’t be on the park.

“It was a big decision, a pressure decision and it probably was not the right decision.

“I knew he was never going to get sent off, that it was never going to be a red card. I think if it had been the other way around it could have been.

“It was the pressure, coming into these big occasions. Some people can deal with it, some people can’t.

“Willie is used to giving me yellow cards – I think he has missed me.”

Asked if he had quizzed Collum about Silva’s challenge, Brown said: “There is no point, it doesn’t change anything. I was disappointed at the time and then he goes on and scores the goal.

“So it is a harsh lesson but for me it is more about us and how we performed.

“A young team having a belief, because a lot of Premiership teams will just come here and defend but we knew we had to try and play.

“We don’t have that huge target man so we had to try and play. We had to move the ball really well, we had a shape and structure. We were fine throughout the whole game. I never felt we would lose that many goals.”

Clement disagreed with Brown’s assessment of Silva’s tackle.

He said: “No, he got a kick on his leg in that action. You need to look closely at the images.

“He showed me there were studs (marks) on the top of his leg.”

Clement took the opportunity to make seven changes to his side.

Mohamed Diomande, the Ivorian midfielder signed from Danish Superliga club Nordsjaelland and Colombian winger Oscar Cortes – on loan from Lens – were handed were handed their first starts, with the latter particularly impresssive in the hour he played.

Clement spoke about a “positive evening” in his assessment.

He said: “After three minutes we could have scored two goals. In football you also need a little bit of luck and that was not on our side today in the finishing, and all respect also to our opponents, who gave their lives to stop the goals, also in the second half by making saves on the goal line.

“It is a positive evening. The other positive thing is to play that kind of game for so many fans, that is maybe the most positive thing of the evening. In that way, I would have wished to give the fans more goals.”