The ACT Brumbies' No.9 will miss the next four weeks as he recovers from a small fracture at the back of a shoulder.

It means he's out of contention for a spot in the Wallabies squad to take on the British and Irish Lions in a once-in-a-career opportunity.

''It's a better result than what I had expected and I'm looking forward to being involved with the Brumbies towards the tail end of the season,'' White said.

''It is a good result considering where I have been with my shoulder and how far surgery can set you back.

''All my focus will be on getting this right for the next game against the Western Force in a month's time.''

White was tipped to be one of the six players added to Test coach Robbie Deans' squad on Tuesday.

The Brumbies guaranteed themselves a place in the play-offs for the first time since 2004 when they beat the Melbourne Rebels at Canberra Stadium on Friday night. But the night was soured when White - standing in as captain for the first time - lasted just nine minutes before he was forced from the field.

The 22-year-old has battled shoulder injuries for the past two seasons.

Brumbies great Joe Roff hoped the excitement of chasing a Super Rugby championship would ease the pain.

''The Lions are the most unique international side that play and they've got so much history behind them so to miss that opportunity is a devastating blow,'' Roff said.

''But taking Tests aside, if you were talking about Nic and if he had the chance to play against the Lions or in a Super Rugby final, then I'm sure he'd take a final with the Brumbies.

''The Lions are once in 12 years but the finals can be just as rare.''

It is the second time White has injured his shoulder this year after he had to leave the field against the Durban Sharks and missed the clash against the Cape Town Stormers in March.

In his absence, Ian Prior slotted straight into the role and helped the Brumbies to a six-try romp against the Rebels.

Prior insists he's ready for more responsibility should White's recovery take longer than expected.

Prior, bound for the Western Force next year, is keen to leave Canberra on a high.

''I've been around a few years now, I've got close to 30 caps now and have been involved in a finals series, so I think I've done all the work and I feel prepared enough if I do need to step up,'' Prior said.

''I've been around, I know the team's patterns inside and out and I definitely feel ready if the opportunity comes up. When you're on the bench anyway you need to be ready. Especially in cutthroat footy.''

Prior was with the Queensland Reds when they won their championship in 2011.

He said team chemistry in Canberra was better than when the Reds claimed the title.