Wayne Bennett has given a compelling vote of confidence to teenage No.6 Isaiya Katoa ahead of the biggest game of his life, as the Dolphins prepare to sink or swim in the big time.

Katoa, preferred over the experienced Anthony Milford for the playmaking job against the Sydney Roosters on Sunday, will make his NRL debut at Suncorp Stadium on the same day the Dolphins make their first appearance in the competition.

The Dolphins held their captain's run at Suncorp on Saturday where Bennett was forced into a late change.

Forward Herman Ese'ese will miss the game with a pectoral injury which AAP has been told is expected to keep him out of action for four weeks. His place on the bench has been taken by Connelly Lemuelu.

Bennett said he had full faith in 19-year-old Katoa, who made his international debut for Tonga at last year's World Cup.

"Isaiya has trained really well. He is a quality player," Bennett said.

"He has got quite a challenge in front of him but I think he is up to it. He is only young but I think there is a fair bit of maturity with him and the rest we are going to have to all watch and see because I had never seen him play until (the trials).

"Training is not the place where you gain your reputation. It is on the football field. He is starting on his journey so let's see what he brings."

Milford was never dropped by Bennett at the Broncos but the coach said he had taken the news well.

"No decision is made lightly particularly with senior players and players that have the quality Anthony has, but there are some things I need him to be better at and that he needs to be better at, and he is working on that," Bennett said.

"He was great. He understood. It wasn't something I was making up. He understands his own weaknesses in his game."

Bennett said the entire club got a boost by the signings of Broncos duo Herbie Farnworth and Tom Flegler for 2024.

"It was a couple of wonderful signings for us and great for the club going forward and the fans, realising they are young men with a lot of football in front of them at the top of their game," Bennett said.

"We are trying to build something players want to come to and be a part of. Obviously a lot of young men have seen an opportunity and that will continue."

Bennett said his team was capable of springing an upset against the Roosters, if they get right the fundamentals he puts such a premium on.

"It is a very special day particularly with the tribute to Arthur (Beetson) and the quality of the opposition we are playing," Bennett said.

"The dawn of the Dolphins has come to a reality."