Just who wears the Broncos' fullback jersey in round one this year will have a "domino effect" on the makeup of the outside back positions and the bench utility spot as well.

The Broncos play the Cowboys in Cairns on Saturday night in a trial that coach Anthony Seibold has already tagged "a genuine shootout" for the fullback position between Jack Bird and Jamayne Isaako.

Seibold is keeping his options open on the No.1, but he has previously shown a liking to carry a bench utility who can cover several positions in the backline.

Bird and Isaako both fit the bill with the former Shark having the extra utility advantage of being able to play in the halves.

One thing is certain about the round one side to play the Cowboys - veteran Darius Boyd will be the left centre.

"He will play left centre. He has had a tremendous pre-season and was outstanding last week [in the trial win over the Capras]," Seibold said.

Glenn: I can't wipe the smile off my face

"Defensively he was great with his talk and he gives a lot of confidence to our squad.

“He’ll have a rest this week and play 60 minutes against the Gold Coast and he will be ready for round one and start at left centre. He has been our best by a distance in that position over the pre-season."

Maroons flyer Corey Oates is on his way back to full fitness and set to play wing against the Gold Coast in the final trial on February 29, while last year's debutant Xavier Coates is a strong chance to play right wing in round one.

That leaves Isaako and Bird in a battle for fullback in Cairns. What Seibold will do with Isaako if he decides to give Bird the nod remains intriguing.

"One thing I will say about Jamayne is that I think he is a fullback and not a winger. I have persisted with him on the wing last year but I think he is a fullback," Seibold said.

“He can play multiple positions and has played on the wing for New Zealand. I go into it with a pretty open mind.

"Jack has been rewarded for his performance from last weekend. Jamayne has to work on some parts of his game and he knows what they are.

“They will split the game this week. I am a big believer that if you get the jersey, and Jack had the number one jersey last week, and you perform well then you keep the jersey.

"Xavier Coates has done a tremendous job on the right wing throughout pre-season and he has got an opportunity to wear that jersey this weekend.

“Oatesy [Corey Oates] is still to come back so Herbie Farnworth gets an opportunity [on the left wing]. It is weight of performance. I can’t be any clearer than that."

Soward's Say: 2020 Broncos

Jake Turpin also gets the chance to make his claim for the hooking role. Turpin will start in Cairns with Andrew McCullough rested after a strong showing in the win over the Capras.

"I know what Macca can do and Turps needs an opportunity to show what he can do at number nine. He’ll play around 40 minutes this week," Seibold said.

"I also wanted to see Cory Paix who has never played against NRL teams.

"We signed him long term and I think at some stage when he does get in the 17 it will be as a 14 because he can play a few positions and has got a lot of speed out of dummy half like someone like a Damien Cook. Macca will come back in and play against the Gold Coast the following week."

That leaves two spots in the Brisbane's spine for round one to be decided.

"Milford and Croft are going to play six seven and whether it is Turpin or Macca in the nine they have done thousands of reps here in the pre-season," Seibold said.

"I do think the number one is a real shootout."