Broncos half Sean O'Sullivan.

Broncos half Sean O'Sullivan says separate training sessions with brothers Matthew and Andrew Johns have played instrumental roles in the sharp learning curve he's been on.

The 20-year-old was at the Roosters last year and got to work with Andrew Johns in his part-time capacity at that club.

During this pre-season, O'Sullivan joined Anthony Milford, Kodi Nikorima, Andrew McCullough and Darius Boyd in travelling to Sydney "a couple of times" to work with Matthew Johns.

Broncos coach Anthony Seibold arranged the trip after having also utilised the older of the two Johns brothers during his time at South Sydney. The goal is to get his spine operating in the "game model" he wants for 2019 as quickly as possible.

"It was good to get some clarity from Matty around how we are going to be playing, with discussions and learning," O'Sullivan told NRL.com after his first game for Brisbane in the 26-12 trial win over Wynnum-Manly.

"I think we all took a lot of out of it, just with the way that Seibs wants to play, the game model and getting our heads around it.

"He was awesome for all of us at giving us defensive tips about what we should look for in defensive lines and how we should communicate with not only the spine but our forwards and our edge."

O'Sullivan feels blessed to have been able to learn from both Johns brothers. While acknowledging both had different takes on rugby league, he said he gleaned a lot.

"At the Roosters we had Joey. Here we have had Matty, and Peter Gentle our assistant coach does a lot with us, so it has been really good to have people mentor you and analyse how you should train and give you those tips," O'Sullivan said.

"Andrew is very big on playing straight and when your forwards are creating power, then you go off the back of that. Matty is more about just playing footy and depicting what you see in defensive lines."

O'Sullivan is unlikely to see NRL action in round one against the Melbourne Storm but has positioned himself as the back-up to first-choice playmakers Anthony Milford or Kodi Nikorima.

O'Sullivan played at five-eighth alongside 17-year-old half Tom Dearden in the trial win over Wynnum. His raking left-foot kicks into space were a highlight.

I think we all took a lot of out of it, just with the way that Seibs wants to play

Sean O'Sullivan on working with Matthew Johns

He said wearing the Broncos colours for the first time in a game was "special".

"I've been training now for a couple of months so it was good to throw on the Broncos jersey and play with some mates and the new little brotherhood that we are forming," he said.

"I'm just a natural left-footer but I’ve got a lot of stuff to work on and still much improvement in my kicking game.

"We do a really good job of working hard on our kicking at training during the week so hopefully the results show in game time."