The budding ACT Brumby had barely finished school when they started the drive from Brisbane to Canberra, but Pasitoa asked his mum to stop just before they crossed the ACT border.

Nerves? No way. The teenager who knocked back NRL clubs to join the Brumbies wanted to be the one to drive into town, which sums up the way he's approaching hopes of playing next year.

Pasitoa, 18, says he won't use age as an excuse as he strives to be the man to fill the sizeable boots of Christian Lealiifano in the chief playmaker role.

He could become one of the youngest players in Brumbies history if he gets his shot, joining the likes of Matt Toomua and Sam Norton-Knight in being teen rookies.

Senior Brumbies Scott Sio and Allan Alaalatoa have already given Pasitoa permission to boss them around on the field, and the schoolboy star is determined to step up.

"I asked to drive the last leg so I could drive into Canberra," Pasitoa grins.

"I understand how lucky I am to have this opportunity, especially at such a young age. So I want to take it with both hands and do anything I can to put my best foot forward.

"I felt like the Brumbies club was the best place for me. I'm loving it so far. Personally, I don't really get nervous anymore. If I get the opportunity to step up, I'll go out and do the best I can.

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"Sometimes I feel like pressure is something you can bring on to yourself. So you have to be confident in your own game and skills."

Pasitoa, the son of a Polynesian father and German mother, is one of three young guns battling for the right to fill Lealiifano's No. 10 jersey in the 2020 season.

It's likely all three will get a crack at some stage during the season and the trio has formed a tight-knight combination to help push each other to be ready for the Super Rugby leap.

Pasitoa, Noah Lolesio and Bayley Kuenzle loom as the playmaker options for coach Dan McKellar, who is excited about the talent he could have available.

Pasitoa grew up in Perth before being recruited to Nudgee College in Brisbane. NRL clubs wanted to recruit him, but the determined youngster wanted to pursue a rugby career.

The Brumbies swooped when Pasitoa was just 16 years old and still had a year remaining at school.

"I came down for one day to check out the facilities and coaches, straight away I liked the values and family orientation the club had," Pasitoa said.

"That was very important to me ... knowing the club has a great history, I was pretty happy with that decision.

"I played league when I was younger, but I've always loved union. The strategy behind it ... I've always watched it and played it."

At 96 kilograms and 184 centimetres, some of Pasitoa's teammates have already described him as a "manchild".

The Brumbies believe he is capable of handling the physicality of playing against men almost twice his age.

He'll also have to boss around Wallabies and Brumbies veterans if he's given the job of steering the side into the Super Rugby campaign.

"Dan just said to me if the opportunity does arise, take it," Pasitoa said.

"When the Wallabies boys came back, that's when I realised I had to step up.

"A lot of people keep bringing up my age, but I don't want to make that my excuse. People keep saying I'm 18, I just want to be Reesjan.

"Training with [the Wallabies] have given me a lot of confidence, Allan Scotty and Folau have been saying make sure you get into us, that's your role. That's helped out a lot and made it easier, but I can always improve."

The Brumbies will have their last training session of the year on Friday after being pushed to their physical and emotional limits in the heat on Thursday.