When Cooper Cronk offered to do the goal-kicking for Sydney Roosters in Saturday night’s match against St George Illawarra, his team-mates thought it was a joke.

Cronk hadn’t kicked a goal since 2008 and his last attempt was in 2013 but the star halfback had no hesitation in putting his hand up for the role after Latrell Mitchell was ruled out with a calf injury at training on Friday.

After 10 shots at training, Cronk surprised Roosters coach Trent Robinson when he landed a sideline conversion of the first try in their 34-12 rout of the Dragons and kicked a further three goals.

With Robinson deciding he didn’t want rookie centre Billy Smith doing the goal-kicking in his NRL debut,  the plan had been for Cronk to do the goal-kicking until interchange prop Siosiua Taukeiaho was on the field but he did such a good job the Tonga international was only given one kick.

“When Latrell was out, Billy Smith is a bit of a goal-kicker but we thought that was too early for him so Cooper said he would do it, and we had a few jokes about him doing it until Siosiua got on the field,” Robinson said.

“He put the first one over the top of the goalposts and it was exceptional, I loved the fact that Cooper would just go out and do that. It was just that challenge there and then he kicked them like that. It was just reward for him.”

Asked if Cronk practiced goal kicking, Robinson said: “Never”.

He volunteered for the role when Mitchell was missing last year but Blake Ferguson was given the job.

“I remember that we were close last year, I remember Cooper saying ‘I will goal kick’. He kicked two or three and they didn’t look like they did tonight so we went we’ll go with someone else,” Robinson said.

“We didn’t want Billy to do it so he just picked the ball up and started goal-kicking. He would have kicked 10 yesterday and then … that’s confidence.”

Besides his goal-kicking, Cronk laid on the three of the Roosters' six tries in a stunning 50-minute performance by the premiers.

The highlight was a 50-metre cross-field kick for winger Daniel Tupou to score in the 27th minute. He attempted a similar kick last weekend against Gold Coast but Mitchell bombed it.

“I thought Cooper played really well today,” Robinson said. “Cooper does some really special stuff. It’s all because he trains hard.”