Just days after being plucked out of his Wanniassa High classroom, Brent Hamlin has a chance to win an ACT Brumbies call up if he impresses coach Stephen Larkham at the Brisbane 10s this weekend.

But the twist is that Larkham, an Australian rugby great, is coming out of retirement to stand next to Hamlin and catch the scrumhalf's passes at the pre-season tournament.

Hamlin's life as a teacher's aide was "flipped upside down" this week when the Brumbies asked him to join the squad after Argentina international Tomas Cubelli suffered a serious knee injury.

The Brumbies have wrapped scrumhalves Joe Powell and Ryan Lonergan in cotton wool for the start of the Super Rugby season against the Canterbury Crusaders on February 25.

But Hamlin, a 25-year-old rugby journeyman and former Australian schoolboy representative, knows the door is open for a chance to earn a Super Rugby deal.

Cubelli faces up to six months on the sideline after rupturing his patellar tendon, but he could be back in time to play the back-end of the Brumbies' campaign.

"I was gutted [for Cubelli] but I was also nervously waiting [to see if the Brumbies called]. It was a bit of a shock to the system," Hamlin said.

"It's going to be an awesome experience passing to [Larkham], I was a bit nervous at training.

"But I think once I get on the field the adrenaline will kick in and hopefully everything goes well.

"There's definitely a window [of opportunity], but Larkham just said to me we won't think about that yet. We'll just focus on the 10s first.

"I work in woodwork and metal work [at Wanniassa High] and with any kids who have a learning disability. Coming into this, my whole world has been flipped upside down."

Cubelli and Lausii Taliauli (anterior cruciate ligament) returned to Canberra on Wednesday night after having surgery in Sydney.

The duo are both off contract at the end of this year and may not play a game as they start their lengthy rehabilitation process.

Larkham is putting faith in Powell and teenager Lonergan to step up, but Hamlin could be drafted into the Super Rugby squad for extra cover.

Larkham will get a front-row seat to the audition when he joins dual international Andrew Walker as the Brumbies' wildcard players in Brisbane.

"We'll see how Brent goes at the 10s and go from there," Larkham said.

"We're not blind to the fact that if we have one more injury to a halfback, then we've only got one left.

"We're going to need coverage there. But we also have confidence in Joe and Ryan to step up going into round one."

Hamlin will be thrust straight into the action, including a clash against French glamour club Toulon, as the only No. 9 in the Brumbies' travelling squad.

The Canberra Royals back is no stranger to the 10s format. The Brumbies recruited him for the World Club 10s in Mauritius last year.

He's also no stranger to the Brumbies set up after being drafted into the club's academy squad in 2008 alongside Matt Toomua, Pat McCabe, Nic White and Robbie Coleman.

But while they all went on to carve out Super Rugby careers, Hamlin played in England and New Zealand before returning to the capital for another crack at the top squad.

"You never know what can happen, this could be that golden opportunity to have a crack," Hamlin said.

"I wasn't even sure I was going to be back in Canberra this year, I was looking at overseas options.

"I only started pre-season training with Royals about two weeks ago and here I am, it's a bit of a shock.

"It's unfortunate for Tomas but for me it's a chance to have another crack and I'm happy to take it."