Arnold, the tallest player in Super Rugby history, will continue his rise from obscurity when the Brumbies play the Melbourne Rebels at AAMI Park on Saturday night.

There are concerns Australian rugby lacks a big, physical second-rower leading into the World Cup, prompting calls for the ARU to entice former NSW Waratah Kane Douglas back into the Test jersey.

But just two games into his Super Rugby career, Arnold is already making waves and wants to show he can throw his 208-centimetre, 120-kilogram frame into brutal battles around the field.

Arnold is refusing to contemplate a Wallabies call-up, despite stamping himself as an imposing figure in his two performances so far.

"To be honest, I can't look that far ahead. I just have to focus on keeping a place in the Brumbies. I've only played two games so far," Arnold said.

"If anything else comes after that, it's a plus. I'm not thinking about the Wallabies at all ... my job is to perform well down here. I just want to test myself against all the best Australian locks.

"It's always good to get the ball in your hands and do the dirty work as well. The physical stuff at the breakdown is always fun."

The Brumbies will name their team on Thursday for the clash against the Rebels in Melbourne, with Arnold to retain his spot in the starting side.

Captain Stephen Moore will return to the starting hooker role after proving he has recovered from a knee reconstruction, while Jesse Mogg is set to play his first game of the year after shoulder surgery four months ago.

Rookie second-rower Blake Enever could get a chance on the bench as the Brumbies aim to stabilise their season after a heart-breaking after-the-siren defeat to the Waikato Chiefs last weekend.

Arnold says he is still finding his feet in the competition, but the giant lock is learning quickly less than three years after he played rugby union for the first time.

He is the equal tallest player in Super Rugby history, standing at 208 centimetres with South African Andriess Bekker.

The Brumbies recruited Arnold despite his lack of experience, putting faith in the 24-year-old, whose background is in rugby league, to stamp himself as a star of the future. He dropped almost 20 kilograms in pre-season training.

"If someone told me a couple of years ago that I'd be playing Super Rugby, I would have told them they are dreaming," Arnold said.

"I was nervous before round one and a bit more relaxed last week, I'm sure as I get more games I'll get more used to it.

"A couple of years ago I was watching the big names and now I get to play with them and against them. It's pretty crazy, i still can't believe I've come this far."

The Brumbies are setting themselves up for a testing month against Australian opponents, taking on all of their derby rivals in a four-week stretch that could set up their finals hopes.

"Hopefully we can get through it as the No.1 Australian team," Arnold said.

"It's going to be tough, it's a good chance to have a crack at the big Australian locks as well to see where I'm at."

Meanwhile, Wallabies coach Michael Cheika is close to finalising his coaching set-up for the World Cup year, with Brumbies mentor Stephen Larkham all but certain to take a position as the back-line expert.

SUPER RUGBY ROUND THREE

Saturday: Melbourne Rebels v ACT Brumbies at AAMI Park, 7.40pm. TV time: Live on Fox Sports 2