Keeley, a Mannering Park product, will be one of a host of young guns starting their first top-flight preseason when the Knights begin training next month.

The 19-year-old has already spent some time with the NRL team, having made an unexpected debut against Canberra in round 23.

Keeley was 18^th man for the match as a reward for his efforts in the lower grades and to get a feel for the side's game-day preparation.

But minutes before kick-off, he was thrust into the actual side after back-rower Tyson Frizell succumbed to a lingering injury.

Keeley, who had only played two games of reserve grade, had thoughts earlier in the day he might get a start but admits his debut still came as a complete shock.

"I did not think I was going to play," the Northern Lakes Warriors junior told the Newcastle Herald.

"But weird enough, I was actually in the shower getting ready to go to the game and I had a bit of a feeling that I was going to debut.

"I did some meditation and stuff to calm down, and it all went and I was fine."

But when Knights coach Adam O'Brien told Keeley he was in, the emotion of the occasion proved overwhelming.

"I just started balling my eyes out," Keeley, who has overcome a neck fracture and dealt with knee issues in recent years, admitted.

"Then all the boys came around and were like, 'let's go kid, you've got this', 'we've got you', 'have fun, enjoy this moment' ... stuff like that."

Keeley had limited involvement playing the last 14 minutes, but he missed a tackle on Raiders prop Josh Papali'i that led to Canberra's match-winning try.

"I come off the field and I was just gutted," he said.

"I hope I never do that again, but it's made me grow as a person and learn how to deal with things.

"I've put that aside, I've debuted and I never thought it would happen so quick.

"Now I just want more and more and more."

Keeley, who played SG Ball this year, had plenty of support from the experienced players after the game.

"They got around me," he said. "Barney had some nice words. Frizell and Klemmer, they spoke about their debuts and how horrible it was.

"They just said, 'this happened, this happened and this happened', and that 'your debut is fine'.

"I was training with first grade for like two weeks and I didn't even do a session with the boys - I was in the reserve-grade team and then I got to play.

"It was a really unique path how I got there."

Keeley's debut came after he represented NSW in the under-19s Origin. He was also part of Newcastle's Jersey Flegg side that made the grand final, but didn't play due to suspension. He reflects on 2022 proudly but is eyeing bigger achievements.

"It was a dream come true and I've had such a nice year, but it's not going to be a good year and good debut if I can't go and back it up for the next few years at the Knights," he said.

"My next game in first grade will be when I'm properly ready for it, and I just can't wait for that.

"I want to nail the first day of preseason and then just go day by day and get fitter and fitter."