Incumbent Australia captain Wilson was injured in contact in the Reds' 27-15 defeat away to the Waikato Chiefs over the weekend, while fellow Wallaby Daugunu is nursing a lower limb problem, the Reds said.
The Reds tumbled from the top of the table to third behind the Chiefs and second-placed Canterbury Crusaders, and can ill-afford another loss against the fifth-placed Brumbies as they look to keep in touch with the leaders.
The Stephen Larkham-coached Brumbies have won their last three matches against the Reds and head into Saturday's clash at Suncorp Stadium after a bye.