The Blues chances of making the Super 15 playoffs will be examined next by the best Australian side in the series.
Numerically, the Brumbies lead their conference, but are in a results decline which has been exacerbated by injury.
Franchise legend George Smith and midfield back Pat McCabe suffered knee injuries in the side's latest loss to the Waratahs and will not be part of the squad for Saturday's match at Eden Park.
The Brumbies are top of the conference but sliding after winning just three of their last eight matches.
That dip, and now the injuries to key players, has provoked doubts about their ability to break their eight-year finals drought.