Dagg injured after dangerous tackle
Dagg, who only recently made his return after a long-term knee injury, was knocked down in a dangerous tackle by Brumbies wing Chance Peni.
The 29-year-old Crusader suffered concussion and a knee injury when he fell awkwardly after Peni tackled him around the head.
Peni has since been cited for the incident. He received an on-field yellow card from referee Jaco Peyper
Dagg is set to go for a scan on his knee to determine the extent of the damage.
Meanwhile, Crusaders lock Luke Romano suffered an ankle injury in training before the match against the Brumbies. He is also set to have a lengthy period on the sidelines and he could potentially miss the All Blacks three-Test series against France in June.
"It is not broken, as we first thought, and he will get an MRI scan on Monday to find exactly what the problem is," Crusaders head coach Scott Robertson confirmed.
The good news for the Crusaders is the flyhalf Richie Mo'unga and centre Jack Goodhue are set to return to training ahead of the match against the Melbourne Rebels.