Cubelli had to be helped from the field after an ugly tackle resulted in his body crumpling underneath him and it was salt in the wounds as arch rivals the NSW Waratahs charged to a 53-17 win.

Cubelli will have scans this week to determine the extent of the damage and whether he faces an extended stint on the sideline with just three weeks left before the Super Rugby campaign begins.

It was a cruel blow to the Brumbies a week after winger Lausii Taliauli suffered a season-ending knee injury in the club's first pre-season trial match.

But coach Stephen Larkham was hopeful of getting good news about his Argentina international, who scored a try and was brilliant in his 36 minutes before being forced to leave the ground in a knee brace.

"He was in a lot of pain, but we'll have to wait to see how he is," Larkham said.

"The brace was precautionary, the positive was that he was able to walk off the field. But with these things we just don't know and we'll have to make an assessment.

"He had some great involvements out there, he's come back after an international season and really wants to improve so we'll see how he is [on Sunday]. It's a bit of a shame."

The Brumbies have two more scrumhalves on their roster, with 11-gamer Joe Powell and uncapped rookie Ryan Lonergan set to be thrust into the firing line if Cubelli is unable to play in round one against the Canterbury Crusaders.

Wharanui Hawera impressed at No. 10 again and is in contention to take flyhalf duties against the Crusaders while dropped ball ruined the Brumbies' chances of finding some rhythm.

The Brumbies already have a new-look line-up after the departure of Stephen Moore, Matt Toomua, Joe Tomane and David Pocock.

Co-captain Christian Lealiifano is unlikely to play this season as he continues treatment for leukaemia and now Taliauli and Cubelli are on an injury list.

Wallabies props Scott Sio and Allan Alaalatoa missed the clash against the Waratahs as they nurse niggling hamstring injuries. Jarrad Butler is also being monitored as he battles a lower-leg complaint

The Brumbies dominated the opening 15 minutes, but that's about where the good news ended as the errors mounted in muggy conditions.

The Waratahs were playing their first trial match and left their Wallabies stars on ice while the Brumbies were playing their second match and had the bulk of their first-string players on the field.

But it was the Waratahs who tore the game apart, running in nine tries to the Brumbies' three and looked in control for most of the contest.

Former Canberra Raider Reece Robinson scored a double while the Brumbies couldn't really get out of second gear in muggy conditions.

"There were a lot of little things that didn't go our way," Larkham said.

"There was enough there to be positive about, but the important thing now is that the guys are honest with themselves in what they need to do.

"The scoreboard didn't look good, but there were enough positive things in that game to move forward in a positive manner."

The Brumbies will use the Brisbane 10s as their final pre-season hitout, with Larkham and dual international Andrew Walker to make playing comebacks at the inaugural tournament next weekend.

AT A GLANCE

NSW WARATAHS 53 (Reece Robinson 2, Jack Dempsey, Jake Gordon, Bryce Hegarty, Andrew Kellaway, Matt Lucas, Irae Simone, Tolu Latu tries; Bryce Hegarty 2, Andrew Deegan, Matt Lucas conversions) bt ACT BRUMBIES 17 (Tomas Cubelli, Josh Mann-Rea, Tom Banks tries; Wharanui Hawera conversion) at Mudgee on Saturday night.