Trailing to Aaron Tshibola's 61st-minute opener but with a man advantage after Ross Millen's dismissal, substitute David Wotherspoon levelled for Saints with five minutes left.

And O'Halloran punished Stuart Findlay's mistake in stoppage time to complete a dramatic late turnaround and secure a 2-1 victory.

It was Saints' first win of the Scottish Premiership season and boss Davidson was delighted for the hero to be a man back from a suspension following his dismissal on the opening day of the season.

"Michael was so disappointed with himself against Dundee United, it was great for him to repay the faith the lads had in him and score the winner," said Davidson.

"He's only played 40 minutes of competitive football but his energy levels were great and to run at that pace and that intensity in the last minute, all credit to him.

"He can be a big player for us, definitely. When I was here before, he scored at Rugby Park, so maybe it's a lucky ground for him, but he has the potential to unlock defences.

"I thought Michael started the second half very well, we changed his position a little bit and he was the main spark for us. He's a really fit guy, he looks after himself and I wasn't going to take him off.

"We played really well against 10 men. We had 10 men against Dundee United and sometimes they can be difficult to break down, so to walk away with three points I'm over the moon."

Kilmarnock manager Alex Dyer insists Findlay must learn from his costly error after his late backpass was picked up by O'Halloran.

Dyer said: "Stuart is honest and he's got enough experience to know what he should have done. It wasn't the right decision.

"When you are down to 10 men you just put it in the stand and regroup but he didn't and we have to learn and he has to learn.

"He played a blind pass, he didn't have a look, his head was down as he played it to the goalkeeper when he should have just cleared it himself."

Dyer had no complaints about Millen's dismissal for a two-footed challenge but felt his side should have been awarded two first-half penalties.

He said: "It's a sending off. I don't think he caught the lad but obviously he's dived in, he's out of control a little and his studs were showing. He's given the ref a decision to make and he's made one.

"I think they were two clear ones (penalties). But we're not getting them at the moment. We will keep plugging away and making those opportunities and hopefully one day one of the refs will give it to us.

"These decisions can make the difference but the mistakes today were our mistakes. We could easily have come away with a draw and we didn't do that."