From awaiting the outcome of a club captain's judiciary hearing to rooming with a future Immortal, North Queensland Toyota Cowboys young gun Mitchell Dunn will never forget the week leading into his NRL debut.

With three of the club's biggest stars away on State of Origin duty and an injury crisis crippling forward stocks, Cowboys head coach Paul Green turned to Dunn, a former five-eighth now second-rower, to place on standby for Matt Scott who had been hit with a grade one shoulder charge by the NRL's match review committee.

After Scott was found guilty and hit with a one-game ban, Dunn's lifelong dream of playing in the NRL became a sudden reality, with Green confirming the youngster would make his first grade debut two nights later in a crucial clash against Manly at Brookvale Oval.

"I was sitting at home for most of the afternoon leading up to Thumper going to the judiciary that night, but I had to get out of the house because I was sick of waiting," Dunn said.

"Toddy Payten eventually sent me a text to say I was in and Greeny called me later on. I was out at dinner, but I didn't really eat anything because I was buzzing so much.

I called my dad and told him to get a flight down to Manly, he just went quiet and I'm pretty sure he teared up a bit. That was a pretty cool experience for the both of us. Mitch Dunn

Dunn's week became even more surreal upon arriving in Sydney on Wednesday afternoon.

With Gavin Cooper in Maroons camp, Dunn was drafted in to bunk down with Cooper's long-time roommate, a bloke by the name of Johnathan Thurston.

"I've been a Cowboys fan pretty much my whole life, so I had to pinch myself a couple of times rooming with him," Dunn said.

"It kept me pretty calm rooming with him, he was a really big help. He's pretty cheeky as well so it was a fun couple of days."

Dunn had to wait for his first taste of NRL action, with Green opting to start the 21-year-old from the interchange.

The former Cowboys NYC skipper took the field in the 27th minute, slotting in at right second-row and making an instant impact, setting centre Enari Tuala free with a crafty offload with his first touch of the ball.

His 36-minute stint included five hit-ups, 19 tackles, two offloads and a tackle bust.

"I started from the bench and I couldn't sit down so I kept doing laps, but the boys were good and calmed me down a lot," Dunn said.

"I really enjoyed it when I was out there, I couldn't stop smiling. It was really fast, a lot faster than any game of footy I've ever played, but that didn't stop me from enjoying it."