All Black Jerome Kaino's involvement in the Test series against the British and Irish Lions is under a cloud after being ruled out of Super Rugby for the next six weeks.
The 77-Test flanker will undergo knee surgery this week and isn't expected to return for the Blues until early June.
That will give Kaino one or possibly two top-flight matches to prove his fitness before the first Test against the Lions in Auckland on June 24.
He could return in time for the Blues' match against the Reds in Apia on June 2.
His only other Blues hit-out could be against the Lions, in the tourists' second match at Eden Park on June 7.
The cause and severity of Kaino's injury is uncertain, with the Blues having sat out a bye round last week.
The 34-year-old had started their previous six games.
The two-time World Cup winner's name was missing from the Blues team named to face the Brumbies in Canberra on Sunday.
His absence clears the way for Akira Ioane to return to the starting line-up at No.8, with Steven Luatua shifting to Kaino's blindside berth.
The dynamic Ioane has made six successive bench appearances after modest efforts when starting the first two games of the season.
The other starting change features George Moala's return at centre outside Sonny Bill Williams. Rieko Ioane moves out one spot to the left wing, with Melani Nanai benched.
Taranaki's Leighton Price, who joined the squad this week due to injury among the Blues locks, features among the reserves.
All Blacks lock Patrick Tuipulotu remains sidelined by a back complaint while outside back Rene Ranger is still out with a sore ankle.
Both teams share the same 3-5 record, with their last starts both comprising losses to the Hurricanes.
The Australian Conference-leading Brumbies went down 56-21 to the defending champions in Napier last week while the Blues were foiled 28-24 in Auckland a week earlier.
Blues to face Brumbies
1. Pauliasi Manu
2. James Parsons
3. Charlie Faumuina
4. Gerard Cowley-Tuioti
6. Steven Luatua
7. Blake Gibson
8. Akira Ioane
9. Augustine Pulu
10. Piers Francis
11. Rieko Ioane
12. Sonny Bill Williams
13. George Moala
14. Matt Duffie
15. Michael Collins
16. Matt Moulds
17. Ofa Tu'ungafasi
18. Sione Mafileo
19. Leighton Price
20. Murphy Taramai
21. Billy Guyton
22. Bryn Gatland
23. Melani Nanai