The Brumbies have unravelled after building a promising lead to fall to the Blues 38-10 in Auckland on Saturday.
Hooker Connal McInerney scored from a Brumbies maul to turn a period of dominance into a 10-7 lead with five minutes to play in the first half at Eden Park.
But they went to the break down 17-10, a penalty after a sloppy restart followed by a weaving try to Finlay Christie that exposed some flaky defence close to the line.
The Blues didn't give Dan McKellar's men a sniff in the second half, AJ Lam's try with 20 minutes to play creating a 31-10 lead before Folau Fainga'a was yellow-carded after continuous Brumbies infringements.
Halfback Nic White completed a successful return from injury, engineering a crafty assault of the short-priced favourites in the first half.
They played close to the lines to expose the Blues' line-out and build momentum from their scrum.
That helped the Brumbies overcome an opening try to the Blues that came after a head-scratching line-out penalty that had everyone confused.
But the Brumbies then allowed the red-headed Christie to duck and dive between five Brumbies close to the line, the visitors finished with 31 missed tackles as the Blues also dominated the breakdown.
"He looked like a ginger running from the sun looking for shade," Blues captain Tom Robinson told the broadcast post-game.
"He's such an awesome dude and it was a huge moment; that little win there got us that momentum.
"In the first half we let them in through what we call dumb-arse penalties ... and we sorted them out in the second half."
It completed a tough slog of three games across the Tasman since their gutting loss to the Queensland Reds in the Super Rugby AU final.
