The 29-year-old will share the duties with lock Sam Carter, who will lead the Super Rugby side on the field.
"You can see a noticeable lift when Christian is around, Brumbies coach Stephen Larkham said on the team's website. "He's a motivator and he's got immense respect from the players.
"I'm optimistic about a possible return for Christian and, whilst playing this season is unlikely, we hope he will be in a position to train with the squad later in the year."
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Lealiifano was diagnosed with leukaemia last August, which rocked his Brumbies and Wallabies team mates, a number of whom shaved their heads in a show of support.
He underwent two chemotherapy treatments and then a bone marrow transplant late last year after his sister proved to be a match for donation.
The Brumbies, the only Australian side to make the playoffs last year, open their season against the Canterbury Crusaders in Christchurch on Feb. 25.
(Reporting by Greg Stutchbury; Editing by John O'Brien; Editing by John O'Brien)
