ACT Brumbies captain Allan Alaalatoa has been suspended for three games for a dangerous tackle, hooker Connal McInerney has a broken leg and could be out for the Super Rugby AU season and prop James Slipper will miss a further 3-5 weeks.

It couldn't have come at the worst time with the Brumbies' grand final rematch against the Queensland Reds at Canberra Stadium on Saturday.

On the bright side, Faingaa has returned to training and was in the selection mix for the Reds, when the only unbeaten teams go head to head.

Alaalatoa will not only miss the Reds for his high shot on Pone Faamausili that earned him a red card.

He'll also miss games against the Western Force and the NSW Waratahs after entering an early guilty plea for his dangerous tackle on the stroke of half-time.

SANZAAR's foul play review committee said the offence warranted a six-week ban, but Alaalatoa's good record and early guilty plea saw that cut in half.

The Brumbies will also be without McInerney, who finished the thrilling victory over the Melbourne Rebels on the weekend in a moon boot.

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He'll undergo surgery for a broken fibula on Tuesday.

While the Brumbies didn't put a timeline on his return - except for "an extended period" - most fractures are a 6-8 week turnaround, with a best-case scenario of about four weeks.

It means McInerney could be out for the rest of the Super Rugby AU season, but should be back for the start of the Trans Tasman competition, if it goes ahead.

Slipper suffered a medial-ligament strain in training last week and will miss a large chunk of the season.

If Faingaa's not ready, then Brumbies coach Dan McKellar will start 21-year-old Lachlan Lonergan and have uncapped Billy Pollard on the bench.

Tom Ross will replace Alaalatoa in the starting line-up, with 21-year-old Archer Holz in line for a bench spot.

Brumbies outside centre Len Ikitau finished the game with his ankle strapped, but he's expected to be fine.

Lock James Tucker played his first Super Rugby AU game in the win over the Rebels, coming off the bench.

The 26-year-old has just five Super Rugby caps during stints at the Canterbury Crusaders and Auckland Blues, struggling with knee injuries.

He backed whoever came in to fill the holes to get the job done - even against the Reds.

"I think the boys that will come are going to do their job really well," Tucker said.

"Everyone's prepared well, had a good pre-season and you've just got to back them to front up and do their job - which is what we're all here to do."

SUPER RUGBY AU ROUND FOUR

Saturday: ACT Brumbies v Queensland Reds at Canberra Stadium, 7.45pm.