But the Wallabies No. 9 has backed replacements Michael Dowsett and Joe Powell to step up and fill the void if he fails to recover in time for the Anzac contest at Canberra Stadium.

White was rotated out of the Brumbies' starting side last week to give Dowsett a chance to start against the Melbourne Rebels, but the 24-year-old injured his ankle at training and his time on the sideline is unknown.

The Brumbies are battling a big injury toll, missing White, Matt Toomua, Tevita Kuridrani, Scott Sio and Jesse Mogg. White's return is more likely against the NSW Waratahs or the Cape Town Stormers in the coming weeks.

"The competition moves very quickly and you've just got to get back out there," White said.

"Things can change pretty quickly. We've certainly got the players there and guys who played their first game [on Saturday night] will be better for it even though we lost.

"Dows and Joe can definitely step up, I thought Michael was really good and controlled the game well. It was hard yakka against the Rebels but hopefully we'll see his skills in some dry weather."

The Brumbies fell to the Rebels 13-8 in rainy conditions at Canberra Stadium, leaving their season dangerously close to disaster.

Coach Stephen Larkham remains optimistic White will be ready to play the Highlanders and ease the Brumbies' injury woes.

White is out of the moon boot and is now wearing a splint while James Dargaville, Jesse Mogg and Tevita Kuridrani are also in contention to make their comebacks from injury if they can get through the full week fo training.

The Brumbies have struggled to build any momentum in the past month and their lead in the Australian conference has been cut to just two points.

But White, who missed an after-the-siren penalty attempt in a 16-14 loss to the Auckland Blues two weeks ago, said the form struggles had done little to dampen the squad's confidence.

"There's still a buzz and feeling we can go all the way, the road has been made a hell of a lot harder," White said.

"But there's still plenty of self belief in the group that we've got the players to do it. If we can get through the next few weeks we'll have a strong contingent coming back from injury at the end of the season.

"Four is probably the limit of losses you can have if you want to finish in the top two. We're at that now, if you want to go a long way in the competition you've got to aim for the top two."

Lausii Taliauli, Nigel Ah Wong and Dowsett made their starting debut against the Rebels, while Powell played his first game from the bench and Rodney Iona was injected when Taliauli was knocked out.

Powerful back-rower Ita Vaea is pushing for a starting XV spot while Larkham said the back line deserved a chance to build combinations.

"It's an unknown with Whitey's injury ... realistically I think we'll give that back-line combination another chance next week to play a bit of rugby," Larkham said.

SUPER RUGBY ROUND 10

Friday: ACT Brumbies v Otago Highlanders at Canberra Stadium, 7.40pm. TV time: Live on Fox Sports 2. Tickets available from Ticketek.