The comparisons are inevitable, but rugby league Immortal Andrew Johns says likening Wests Tigers wonderkid Luke Brooks to any other player would put too much pressure on the prodigious teenager.

Brooks, whose build and style of play had many reminiscing about a young Johns, produced a debut to remember against St George Illawarra on Saturday, with a try and two try-assists in a 34-18 win.

Johns made a similar lasting first impression when he tallied 23 points in his run-on debut against South Sydney in 1994, but the former Test and NSW Origin star said any comparisons to 18-year-old Brooks were not fair.

"I don't want to compare him to anyone because he's his own man and I don't want to put pressure on him, because he's got so far to go," Johns told Triple M.

"But I think everyone can sit back and see how exciting this young guy is.

"I'm pretty sure this debut is one I'll sit back for the rest of my life and remember this one."

Brooks' debut resulted in Benji Marshall shifting out to the centres - a position he has not played since the very early days of his NRL career.

Freed of the playmaking responsibility Marshall thrived - in what could be a pointer to his role with Auckland when he switches to rugby union in 2014.

He ran the ball 16 times for 133 metres, smashing his previous best effort this season of nine runs in one match.

"Obviously I've been struggling with the running game a little bit," Marshall admitted after the win over the Dragons.

"(It) gave me an opportunity to not worry about ball-playing and just worry about running and I thought Brooksy stood up and took control when he needed to."

While coach Michael Potter would love to continue with the experiment for the next two weeks, Brooks will be back in the under 20s next week due to the limitations of the salary cap.

Chief executive Grant Mayer said the Tigers were comfortable with the NRL's ruling on the matter, with Brooks only given an exemption to play against the Dragons and take the Tigers beyond their second tier salary cap limit because both sides were out of finals contention.

"We know the rules (and) understand exactly how this was going to play out," Mayer told AAP.

"The NRL has made it very clear and we've accepted that.

"To give the guy a taste (against the Dragons) was great but we know he won't be there next week."

Asked if it was wrong of the league to deny Brooks another game, Mayer said"

"Absolutely not ... I'm sure the fans would say it is wrong, but you've got to take your time with him.

"We'll see more of him next year, so (fans need to) be patient."