The only problem is the 118kg wrecking ball is unsure when he will get an opportunity to force his way into the side as he continues his recovery from a knee injury.

The Brumbies will take on the Free State Cheetahs at Canberra Stadium on Saturday afternoon in their second match of the season, but Auelua will not be considered for selection with an undefined timeframe on his rehabilitation.

Auelua injured his knee while playing in Japan before joining the Brumbies.

It's not the ideal start to his Super Rugby career. But he's determined to prove he can be a powerhouse in the competition and insists he's happy to bide his time until given the green light.

''I'm pretty comfortable at 118-119kg, I don't think I want to go any lighter than that,'' Auelua said.

''I've been a big boy and heavy all my life so I can carry that weight around and I think that will be good to me.

''The strength and conditioning guys we've got are amazing and they're doing a great job working with me.

''When I get back I will definitely be giving it my all … I want do something special and I don't want to look back at tapes and do nothing on the field.''

The Brumbies only managed to win back-to-back games once last season.

But they can get their 2012 campaign off to a perfect start if they beat the Cheetahs at home.

Coach Jake White will make a minor adjustment in his back line after fullback Robbie Coleman injured his groin in the opening round.

His absence opens the door for Jesse Mogg to be thrust into the No. 15 jumper with Pat McCabe expected to return on the wing.

Mogg is the leading candidate to take over the fullback duties because White prefers to have a left-foot kicker at the back to combine with right-footer Matt Toomua at flyhalf.

McCabe was supposed to make his return from a shoulder reconstruction today.

But the relentless rain in Canberra forced the ACT XV match against Tonga A to be cancelled.

It is unknown how White will set up his pack to play the Cheetahs.

To combat the Western Force's David Pocock and Nathan Sharpe in the first round, White opted for a beefed up back row and multiple lineout options.

The coach has declared he intends to use a ''horses for courses'' selection process and is happy to make changes to his team if he feels it will help the Brumbies win.

Auelua is the third specialist No. 8 on the Brumbies roster.

Captain Ben Mowen will have the position for most of the season while Ita Vaea was reinvented as an openside flanker against the Force.

Auelua admits he doesn't know where he fits into White's plans.

But after spending time at lock, flanker and No. 8, the 28-year-old is happy to jump into any position which becomes available.

''It's a weird situation, but hopefully I can get a spot,'' Auelua said.

''I don't want to just make up the numbers, I want to come in and have an impact for the squad and an influence for the team.

''It will be a while [before I'm right], but when I get my shot I will give it 100 per cent and do my best for the boys.''