Lafferty was tasked with finding the back of the net in the absence of injured striker Nikica Jelavic and responded with the only goal of the game to keep the Scottish champions top of the Clydesdale Bank Premier League.

The Northern Irishman has courted controversy in the past but McCoist feels he is now weighing in with crucial goals.

He said: "He is some boy. He's got a bit of everything in his game and he does score goals, he scores important goals.

"There is still massive amounts of improvement to come from him and there are things in his game that we will work on.

"But when you've got guys like Lafferty, Steven Naismith, Gregg Wylde and Steven Davis who just want to do well, you will settle for that. I love working with boys like that.

"It was another top-class finish from Lafferty. I always look at boys who score goals and you get different types of goalscorers but the best goalscorer is one who scores important goals and he can do that."

McCoist - who is "very, very hopeful" that Jelavic will recover from a knee injury ahead of next week's Old Firm derby admits Johnny Russell's straight red card for a headbutt on Kirk Broadfoot after half an hour was the turning point in the game.

He said: "Of course it was. I think it was a moment of madness from young Russell.

"He is a very good young player, a good young prospect with a good future ahead of him. He realises he has made a mistake and that you can't do that.

"The referee was 100% correct with the decision."

United could also have had a penalty when Danny Swanson went to ground under pressure from Dorin Goian when the game was still deadlocked but the player was booked for diving instead.

Asked if it was a spot-kick, McCoist said: "I'll be honest, I really don't know.

"What I will say is that the referee was a lot closer than I was and he called it right away. I'm not shirking the issue, if I thought it was a penalty I would tell you.

"I don't know because my angle wasn't good. There are always talking points and I will look at it again."

United boss Peter Houston felt the red card and the penalty claim were the key moments in a closely-fought match.

He said: "The game was made more difficult by the sending-off and the penalty kick.

"I've seen it a number of times and in my opinion it was a stonewall penalty kick. I'm disappointed with that decision."

On the sending-off, he added: "I've no complaints at all. There is no place for anybody wanting to put their head on another guy's head.

"Johnny is a young boy and he will hopefully learn from this. Johnny realises his mistake and he's gutted about it. The sooner he learns, the better for me."