Boss Walter Smith paid tribute to the scorer after he helped the Scottish champions move to within potentially two games of securing the Clydesdale Bank Premier League title.
Lafferty was drafted into the starting line-up, with top goalscorer Kris Boyd left on the bench.
"I'm pleased for him," he said.
"He started the game well and played very well in the second half. It was a terrific goal. At that stage of the game we needed the gap to be wider and we were delighted he got the goal.
"If you look at the goals he scored previously prior to this season, playing wide on the left, his goals have been excellent. This season has not been so clever so we are glad he got the goal."
Smith added: "On reflection I think I've been a bit unfair to Kris Boyd because he went straight back into the team after his hernia operation and in hindsight maybe we should have let him get his fitness levels up.
"We have a break now and hopefully that will allow him to come back all the better for it against Dundee United."
Smith said: "It was always going to be an awkward one for us tonight with Aberdeen not getting a top six place.
"They defended well in the early stages and it was going to take something special, which Steven Davis came up with.
"There was a little slackness after the second goal and that allowed Aberdeen to get a goal.
"But I'm delighted the win leaves us with two games in the final six to retain the championship. It's a good situation for us.
"It's a really good position to be in and I'm sure any team in the league would like to be in this position. I know it's boring to say but we now just take the games on an individual basis."