The Birmingham City loanee leads the way in the Cappielow club’s goal chart alongside Jon Scullion, having netted three times in 10 appearances so far this term.

He feels he had the opportunities to add to that tally against the runaway Championship leaders in Ton’s 4-0 loss at the weekend.

And the 20-year-old perfectionist was especially frustrated not to have converted after following up on a rebound after goalkeeper Wes Foderingham denied Michael Tidser on 42 minutes.

Johnstone told the Tele: “We had some chances, and I concentrated on just hitting the target when I should have just put the laces through it.

“I think I’ve tried to be too cute and focused on hitting the target — next time I’ll certainly be putting the laces through [a chance like] that.

“Do I think I should have scored that chance? Yeah, as a striker you’re a perfectionist and I’m disappointed with that. I should have scored.

“There was another chance when I really thought I was clean through but Lee Wallace has come out of nowhere.

“That’s the quality of player he is.

“He’s played at national level obviously so he’s a high calibre defender and has that in his locker.

“It would have been nice to score and obviously myself and Alex [Samuel] had a couple of opportunities, but it wasn’t to be.” Johnstone was named the sponsors’ man of the match, and he hopes the Birmingham coaching staff were tuned into BT Sports to get an indication of what he could be capable of at St Andrews.

He added: “Games like Sunday were why I came here. You’ve got these things in mind, games against Rangers, Hibs and the derby with St Mirren, when you make your decision.

“That was the type of game people down south will be looking at. I was with the centre-half Rob Kiernan last year at Birmingham, and he’s an [English] Championship defender.

“If I’m doing well against these types of players then it gives me an indication that in the future I can do it at a high level.” In terms of the overall outcome, Johnstone thinks failing to hold out longer than 12 minutes ultimately proved Ton’s undoing against an excellent Rangers team.

He said: “I was disappointed that we conceded so early on. If we had lasted a little bit longer and weathered the storm then it gives you that bit of hope of getting something from the game.

“Obviously going a goal down and then two goals down so early done us in a little bit, but take nothing away from Rangers, they’re a quality side and punished us in the final third.”