Saints had the better of the first half until Stuart McCaffrey put through his own net just before the break, and Nacho Novo came off the substitutes' bench to seal the victory late on.

McCoist told BBC1 Scotland: "First and foremost, we knew it would be a very difficult tie for us.

"I'm just really, really pleased that we've come through okay unscathed and it was a good result.

"We had a couple of shaky moments in the first half but, it being a cup tie, the result was the most important thing so obviously we're delighted."

Asked if Saints had given Rangers a real examination, McCoist said: "They absolutely did but, to be fair, it was no surprise to us - we knew they would.

"They're not top of their league and undefeated in 14 games for any other reason than that - they're a good side.

"I think the goalkeeper had a couple of great saves in the first half. Obviously, he had to be on top of his game and he was, thankfully.

"But I thought we weathered the storm a little bit and scored a couple of very good goals."

Kris Boyd started tonight's game less than a week after he had looked certain to join Birmingham before the move broke down over personal terms.

There are reports the transfer could be revived but McCoist insisted there had been no further contact from the midlands club.

He said: "Not a thing. I think he handled himself very well today.

"People were asking the question, would it affect him?

"I thought he put himself about well and did well for the first goal.

"But there are no further developments and I am happy he was in the right team tonight."