Brumby Matt Toomua injured his adductor while playing for the Wallabies.

Brumby Matt Toomua injured his adductor while playing for the Wallabies. Photo: Getty Images

The ACT Brumbies are adamant a nightmare injury toll won't derail their championship bid after Wallabies star Matt Toomua joined a growing casualty ward, which looms as the biggest threat to their Super Rugby finals hopes.

The Brumbies are counting the costs of a disastrous three-week competition break for international rugby, which has put several key players in doubt for the crucial clash against the NSW Waratahs on Saturday night.

Three players need scans on Monday, including Toomua (adductor), Josh Mann-Rea (hamstring) and Joseph Tomane (cheekbone), to determine if they will be able to take on the Waratahs at ANZ Stadium.

Pat McCabe (shoulder) is rated a 50-50 chance to play, Sam Carter (ankle) is still in a moon boot and racing to be fit for the clash against the Western Force on July 11 and Stephen Moore (knee) is out for the rest of the season.

The Brumbies will sweat on scan results with Mann-Rea's potential absence creating hooker chaos, with Moore and Siliva Siliva (knee and ankle) already out of action for the rest of the year.

If Mann-Rea is out, it will leave the Brumbies without a recognised hooker on their roster with the club to draft in Super Rugby journeyman Luke Holmes and use prop Ruaidhri Murphy as his back up.

But in good news for the Brumbies, Test prop Ben Alexander is fit after missing the Wallabies series to recover from a neck problem and Tomane is pushing for selection after missing more than a month because of a fractured cheekbone.

"Moore's out, Carter's out, Mann-Rea potential, Toomua has adductor strain, McCabe is about 50-50 at best ... put them together and it's going to be a big week," said Brumbies director of rugby Laurie Fisher.

"We'll rely on what we do, and the depth of our squad. It will test character and spirit.

"Whatever 15 or 23 we put out there, we'll have a red-hot crack. We just have to wait to see who we can put on that team list. We might get a whole heap of good news, we might get a whole heap of bad news, or we might get a bit of both.

"We've got four players who are on the doubtful list at this stage ... it's going to be a massive test for the work we've done in the last two or three years."

Toomua played 50 minutes in the Wallabies' third Test win against France before leaving the field.

The Brumbies' on-field success has transferred to international duties for their stars, but they suffered four crucial injuries during the Test break to add to David Pocock (knee) and Siliva already being on the sideline.

Toomua, McCabe, Moore and Carter were all injured while on Wallabies duties.

Mann-Rea's injury while playing for Gungahlin leaves the Brumbies without a hooker in a 35-man squad.

But Fisher is liklely to stick with former Waratahs, Force and Rebels rake Holmes, who was drafted in from Sydney club rugby when Moore got injured, with Murphy as his deputy because both players know the Brumbies system.

The Brumbies will resume training on Monday and the team that lost the final to the Blues at the Singapore world club 10s tournament on Sunday will also return to the capital.

The Brumbies need to win their last two games of the regular season to guarantee themselves a play-off spot and need to beat the Waratahs to stay alive in the race for Australia's No.1 ranking.

If the injuries weren't already a problem, the Brumbies also have to figure out a way to stop 140-kilogram Wallabies monster Will Skelton.

Skelton starred in his starting debut for the Wallabies on Saturday night and will be riding high when the Super Rugby campaign restarts.

The 22-year-old giant started on the bench when the Brumbies beat the Waratahs in Canberra earlier this year, but NSW coach Michael Cheika could opt to inject him straight into the starting pack.

"We just have to defend well, we have to play the game with good tempo and control possession," Fisher said.

"You can't single [Skelton] out, whoever has the job of tackling him has to tackle him. If you give him a run off and you let him off, you're in trouble.

"There's no special tactics, tackling is tackling. It doesn't matter whether a bloke is 140 kilograms or 70 kilograms, you've just got to tackle the bloke."

SUPER RUGBY ROUND 17
Saturday: NSW Waratahs v ACT Brumbies at ANZ Stadium, 7.40pm. TV time: Live on Fox Sports 2.

BRUMBIES INJURY WARD

MATT TOOMUA
Adductor, needs scans

JOSH MANN-REA
Hamstring, needs scan

JOSEPH TOMANE
Cheekbone, needs scan

PAT McCABE
Shoulder, 50-50 chance to play

SAM CARTER
Ankle, aiming to be back July 11

STEPHEN MOORE
Knee, out for season