Brumbies coach Stephen Larkham and former Wallabies warrior Pat McCabe have thrown their support behind Coleman for his mission to replace injured Wallabies back Matt Toomua for a crucial clash against the Pretoria Bulls on Friday night.

Toomua is battling a nagging knee injury and it remains unclear how long he will be out of action, opening the door for Queanbeyan junior Coleman to return to the position where he started his Super Rugby career.

Since partnering Matt Giteau as the Brumbies flyhalf and inside centre combination in 2011, Coleman has played every backline position except for outside centre.

That's why Larkham had no hesitation throwing him into a midfield battle with the rampaging Bulls at Canberra Stadium as the Brumbies fight to stop their season slipping away.

Toomua and Christian Lealiifano have formed a playmaking duo for every game so far this season, but Toomua's knee problem has forced Larkham to search for someone to rejig the attack.

"Robbie loves to get his hands on the ball so he's going to be full of energy when we get the ball," Larkham said.

"He's going to add a different dimension to our attack, I think he adds a bit of spark there and sees the game really well. Defensively, he's up for the contest."

The Brumbies will run into the red-hot Bulls in Canberra, with the visitors winning their past five games and losing only one match this year.

In contrast, the Brumbies have slipped down the ladder as they battle their way through a mid-season slump and have won just two of their past six matches.

The club has been hit with back-ine injury blows in recent weeks, losing Toomua for a yet-to-be-determined period, Joseph Tomane and Henry Speight.

However, they have been bolstered by the return of Stephen Moore, Ben Alexander and Scott Sio to the front row, and Rory Arnold is starting at lock.

Larkham asked McCabe to return to the Brumbies' inner sanctum on Thursday to present the players with their jerseys, less than two years after her was forced to retire when he broke his neck a third time.

McCabe had a reputation as one of the toughest players in world rugby, refusing to take a backward step as he filled almost every position in the backline.

"The potential is definitely there, it's just that we've only seen it in glimpses over the past four weeks," McCabe said.

"The guys will be desperate to turn it around. It's certainly through no lack of effort or want. It's tiny margins and it won't take much to turn it around."

"Robbie has an outstanding skill-set, he can do anything and I think he's going to be a great injection there. Particularly if he's given some space against a pretty big Bulls forward pack, he could run amok."

SUPER RUGBY ROUND 11

Friday: ACT Brumbies v Pretoria Bulls at Canberra Stadium, 7.45pm. TV time: Live on Fox Sports 2. Tickets available from Ticketek.

Brumbies team: 15. Aidan Toua, 14. James Dargaville, 13. Tevita Kuridrani, 12. Robbie Coleman, 11. Nigel Ah Wong, 10. Christian Lealiifano, 9. Tomas Cubelli, 8. Jarrad Butler, 7. David Pocock, 6. Scott Fardy, 5. Sam Carter, 4. Rory Arnold, 3. Ben Alexander, 2. Stephen Moore, 1. Scott Sio. Reserves: 16. Josh Mann-Rea, 17. Allan Alaalatoa, 18. Ruan Smith, 19. Tom Staniforth, 20. Blake Enever, 21. Jordan Smiler, 22. Joe Powell, 23. Lausii Taliauli.

Bulls team: 15. SP Marais, 14. Travis Ismaiel, 13. Jesse Kriel, 12. Jan Serfontein, 11. Bjorn Basson, 10. Francois Brummer, 9. Piet van Zyl, 8. Hanro Liebenberg, 7. Arno Botha, 6. Lappies Labuschagne, 5. Marvin Orie, 4. RG Snyman, 3. Marcel van der Merwe, 2. Adriaan Strauss, 1. Trevor Nyakane. Reserves:16. Bandise Maku, 17. Lizo Gqoboka, 18. Werner Kruger, 19. Jannes Kirsten, 20. Roelof Smit, 21. Rudy Paige, 22. Tian Schoeman, 23. Dan Kriel.