Wallabies back Christian Lealiifano has been diagnosed with Leukaemia.
The Brumbies co-captain, who was not named in the Wallabies squad on Friday is currently in hospital receiving treatment.
The Brumbies said, in a statement, that after a brief illness, investigations revealed the disease.
"At the moment it's just a matter of ensuring Christian receives the best care and support he can at this time," Brumbies chief Phil Thomson said.
"He is one of the most respected players within this group and this news has come as a huge shock to all of our players, coaches and staff.
"Everyone knows that Christian is an amazing young man, an important member of this team and of the Canberra community."