McKellar will finalise his side on Wednesday for the Brumbies' clash against the Melbourne Rebels in the first game of the Super Rugby season on Friday night.

Valetini is expected to secure a back-row spot alongside David Pocock in the starting side, with Lachlan McCaffrey emerging as the front-runner for the No. 8 role.

The three-way combination means Pete Samu will likely start his Brumbies career on the bench after playing just 35 minutes during the pre-season.

McKellar has been weighing up selections and Wallabies requests to manage player workloads has added an extra layer of complication to finalising a starting XV.

Pocock, Allan Alaalatoa and Scott Sio have been rested from both trial matches. Pocock is likely to be thrown straight back into the No. 7 role, while James Slipper's arrival will help share the front-row responsibilities.

Valetini is regarded as one of the players to watch in Australia this year despite injury limiting him to just three games in his debut season last year.

"[Valetini] has been looking really good and it's great to have Pete Samu there, he certainly adds depth and a lot of experience," Pocock said.

"We've got Tommy Cusack, who's Mr Reliable and Locky McCaffrey. It's a pretty solid season and I'm pretty sure everyone will get game time over the year.

"[Valetini] is getting there. He's had a couple of injuries, which has really minimised how much game time he's got. I'm really looking forward to seeing what he can do this year and stepping up, he's been around the program for three years now ... I think this will be a good year for him."

The Brumbies will be starting the season at home for the first time in three years and are desperate to get revenge against the Rebels after losing both derbies last season.

The Rebels are the favourites to win the Australian conference this year, boasting Wallabies in every position and on the bench.

Quade Cooper is set to end his Super Rugby exile and reignite a halves partnership with Will Genia, while the Brumbies are set to turn to Joe Powell and Christian Lealiifano to guide them around the park.

Powell will use the Super Rugby season as his selection audition for the World Cup after being left out of the Wallabies' spring tour squad at the end of last year.

"I love playing against [Genia], he's the best No. 9 in the country at the moment so it's good to see where you stand," Powell said.

"To be honest I haven't really put any thought into [Wallabies selection] at all. It's a long way away, we've got a full Super Rugby season ahead of us. Obviously you want to be back in the fold there, so we'll see what happens during the season."

SUPER RUGBY ROUND ONE

Friday: ACT Brumbies v Melbourne Rebels at Canberra Stadium, 7.45pm.

rumbies: 1. James Slipper, 2. Folau Faingaa, 3. Allan Alaalatoa, 4. Rory Arnold, 5. Sam Carter, 6. Rob Valetini, 7. David Pocock, 8. Lachlan McCaffrey, 9. Joe Powell, 10. Christian Lealiifano, 11. Toni Pulu, 12. Irae Simone, 13. Tevita Kuridrani, 14. Henry Speight, 15. Tom Banks. Reserves: 16. Josh Mann-Rea, 17. Scott Sio, 18. Les