Celtic debutant Alistair Johnston admits he was surprised his side did not get a penalty during Monday's 2-2 derby draw with Rangers at Ibrox.

But referee John Beaton played on and video assistant referee Willie Collum did not call him to the monitor.

"I was actually in the box, and put my hand up because it just felt something unnatural had happened," said Johnston.

"It happened so fast, you couldn't really tell. After the match, you see the replay, and I think it's hard to argue that is a natural hand position.

"As a defender especially, you put your hands up there, you generally run the risk.

"So for me obviously I thought it was a pen. I sound a little biased here but it is what it is. It's a 90-minute match and there were so many other moments where we could have done better, where you are not putting the match in someone else's control.

"We don't look at it like VAR screwed us - it was a decision that went against us, but there will be plenty that hopefully go for us and others that go against us.

"All we ask for is just consistency, that's the biggest thing you want as a footballer.

"As a defender especially now, you are pretty much told you can only defend with your hands at your side, and you see a lad putting his hands to his face and not getting called for a pen.

"If you see one of us give up one in a couple of weeks where it's similar and they call it, there are going to be some questions asked. As long as it's consistent, we are happy with it."

Canada international Johnston enjoyed his first taste of Scottish football, adding that there is "lots of room for growth".

"There's still so many adjustments and tweaks I want to make, but for a first performance in a place like that, I'm not going to be too hard on myself," he said.

"It was a good start and if every match is like that in terms of the atmosphere, it will be a pretty fun time here."