Young Sharks playmaker Kyle Flanagan, son of head coach Shane, was handed a surprise NRL debut against Newcastle on Sunday and produced the sort of performance that suggests he has the mental fortitude to play plenty more at this level.

The 19-year-old said after the 38-12 win he was focused on getting involved early but not overplaying his hand and letting senior half Chad Townsend run the team.

He managed both tasks; Newcastle's first possession – a Shaun Kenny-Dowall return from a Townsend kick a minute into the game – resulted in a Knights penalty when Flanagan collected the former Rooster high with a swinging arm.

"I was a bit shocked [to find out I'd be debuting], I thought my chance to play this season was over but I got an opportunity and I was super excited," Flanagan said.

"The older blokes were pretty good, they made my job pretty simple, make my tackles and play well."

Some encouragement from senior players like Luke Lewis and Paul Gallen were part of the reason for his over-eagerness on that first challenge.

"Yeah that's what I mean, I wanted to make my first tackle, I went looking for it. Missed my technique there but I just wanted to make my first tackle," Flanagan laughed when reminded of the penalty.

"I didn't want to overplay my hand in my first game, I can build off that … It's their team, it's not my team, I just wanted to do my job and play well.

"There's boys that have played Origin and for Australia. Lewy's last home game. It's pretty special."

Match Highlights: Sharks v Knights - Round 24, 2018

Flanagan received the good news from his father on Friday morning when he came in for scheduled goal-kicking training, with senior five-eighth Matt Moylan forced to sit out a week with a minor hamstring complaint.

Moylan is expected to return in round 25, meaning Flanagan's NRL debut is likely to be his only NRL appearance of 2018.

"I knew probably Thursday night we'd need a change there," Shane Flanagan said after the game.

"I told him Friday morning once we got the scans on Matty. He's been ready for a while … He's played well for Newtown and come through the system."

Asked for his assessment on his newest playmaker, Flanagan joked: "Good kid, good parents!

"I thought as the game went on he got better. His first tackle he clocked Shaun Kenny-Dowall on the chin to give a penalty away. As the game went on he got more involved and was more comfortable.

"I knew he was going to play first grade at some stage, I just didn't know when."

Shane Flanagan said he was pleased Kyle got to debut alongside the retiring Luke Lewis plus a host of other experienced rep stars like Paul Gallen, Aaron Woods, Matt Prior, Andrew Fifita and Josh Dugan.

Lewis, who played his final ever game at Southern Cross Group Stadium while Kyle played his first, had plenty of praise for the up-and-coming halfback.

"A lot of us said to him, 'don't think too much about it, just go out and play your game and let Chaddy sort out the game plan'. I think he did really well to be honest, his football over the last 12 months from what I've seen, especially with him in pre-season, he's been ready to take that step.

"I knew it would be hard for Flanno to pick him because it's your own son but he's done everything, ticked all the boxes all year, put his hand up.

"I thought he played outstanding for a half with all that pressure put on him.

"We didn't play our best football in the first 40 minutes so that would have put more pressure on him again but nothing really fazed him. He got out there and made his tackles, got in the mix of it pretty early, kicked pretty well and stuck to the structure of our team.

"He's got a big future and got a lot to work on. I'm just glad I got a chance to play with him so I can look back in five or six years and say I got to play with Flanno which is pretty cool as well."