Wallabies star David Pocock is among three forced changes for the Brumbies' Super Rugby clash with the Chiefs on Saturday night.
Pocock was concussed five minutes into last week's season-opener against the Melbourne Rebels, while wingers Henry Speight (hip) and Toni Pulu (cheekbone) also suffered injuries in the 34-27 defeat.
It was Pocock's third serious head knock in a year, ensuring the Brumbies took no risks with the John Eales medallist.
But he is a chance to return for the round three trip to play the Hurricanes on March 1.
Pulu is facing up to eight weeks on the sidelines while the ACT franchise don't have a time frame on Speight's return.
Pocock has been replaced at openside flanker by Tom Cusack, who is coincidentally returning for his first game since battling multiple concussions last year.
Andy Muirhead and Chance Peni slot into Speight and Pulu's spots.
Peni will be desperate to make amends for a horror 2018 where he served a total of 13 weeks suspended for two dangerous lifting tackles.
Brumbies coach Dan McKellar is backing the former NRL-listed player to shine.
"(Peni) understands he's got to make a couple of adjustments around tackle technique and making sure he gets those right," McKellar said.
"He's done a lot of work on it in the background and we're comfortable he'll perform well.
"He gets a chance now that probably a week ago he didn't see coming so I'm pleased for him and excited."
The Brumbies will have to end a five-year drought against the Chiefs.
The Hamilton-based side will be desperate to avoid losing three-straight for the first time since 2014 after going down to the Highlanders last week to go with their 2018 quarter-final defeat.
Brumbies: Tom Banks, Chance Peni, Tevita Kuridrani, Irae Simone, Andy Muirhead, Christian Lealiifano (capt), Joe Powell, Lachlan McCaffrey, Tom Cusack, Rob Valetini, Sam Carter, Rory Arnold, Allan Alaalatoa, Folau Fainga'a. James Slipper. Res: Josh Mann-Rea, Scott Sio, Leslie Leuluaialii-Makin, Blake Enever, Pete Samu, Matt Lucas, Wharenui Hawera, Tom Wright.
Australian Associated Press