David Pocock (calf) and Allan Alaalatoa (wrist) are in danger of being ruled out of the Brumbies' clash against the NSW Waratahs in what would be a major blow before the round-five clash.

Wallabies prop Alaalatoa has been cleared of major damage to his wrist, but could be ruled out for the next two games after a costly loss to the Melbourne Rebels last week.

His absence could pave the way for Canberra junior Tom Ross to be added to the game-day squad for the first time to partner Les Leuluaialii-Makin in the tighthead rotation against the Waratahs.

The Brumbies are expected to take a cautious approach with Pocock, who injured his calf at a Wallabies camp in January and was concussed in round one.

The loss of Pocock will be somewhat offset by the return of Lachlan McCaffrey, who was rotated last week, but the breakdown specialist is one of the best in the world and he will leave a massive hole in the Brumbies line-up.

The Brumbies, however, are well-versed at being without Pocock and won their only game of the year when the superstar flanker missed the round-two match against the Waikato Chiefs.

Injuries have been a thorn in the Brumbies' side so far this season, losing Pocock, Henry Speight and Toni Pulu after the first game of the year.

Lausii Taliauli is a week-to-week proposition after injuring his knee in a trial match, while Ben Hyne will miss the entire season after rupturing his anterior cruciate ligament in December.

But injuries also mean opportunity. Tom Cusack has proved more than capable as a No. 7 replacement and McCaffrey adds experience to the No. 8 role, while 20-year-old Ross will be thrown into the derby.

Ross, the nephew of Canberra Raiders great Bradley Clyde, has been a rising star in the ACT rugby ranks and has been rewarded with a full-time Super Rugby contract this year.

The other layer of complication this week is the absence of 12 Brumbies, who are in Sydney for a Wallabies' World Cup planning meeting.

They won't return to Canberra until Tuesday night, leaving the Brumbies just one and a half training days to prepare as a full squad.

The Brumbies have won just one of four games so far this year and former skipper Sam Carter says the players must be brutally honest about their early-season errors after a second-half fade in Melbourne.

"We want to lock down our detail and be as best prepared as we can to go on Friday night," Carter said. "We've been making errors ... if we look at the review and we're honest, we should be able to turn it around.

"We need to look at where we went wrong and what we can do better in those situations. Little things that can turn the game back in our favour."

The Brumbies squandered chances against the Rebels, coughing up a 16-point lead at half-time to lose by three points.

SUPER RUGBY ROUND FIVE

Friday: ACT Brumbies v NSW Waratahs at Canberra Stadum, 7.45pm. Tickets available from Ticketek.