The Brumbies ended the Reds' 12-game winning streak at Suncorp Stadium, after upsetting their Aussie rivals 22-14 on Saturday.
It was top versus bottom, but the underdogs prevailed in what was a magnificent performance by the Brumbies with skipper Matt Giteau kicking a penalty on full-time to deny the Reds a losing bonus point.
Giteau contributed 17 points with the boot in a polished performance to help his team to their third win of the season, restoring some pride in the process.
The Reds stay top of the pile, but could play out the remainder of the season without star winger Digby Ioane who was stretchered off after his head connected with Ita Vaea in a tackle eight minutes into the second half.
The injuries didn't end there for the defeated Reds. Full-back Ben Lucas sustained an elbow injury and Will Genia limped off with a leg problem late in the game on a miserable night for the home side.
The Brumbies were always in control after leading 19-11 at the break thanks to a try from Stephen Moore and a conversion and four penalties by Matt Giteau.
Lucas managed to dot down for the Reds just before the break, but the Queenslanders could only muster one penalty from Quade Cooper, who had slotted two first-half penalties, after the break.
The Brumbies stunned the home side in the first half, dominating the collisions from the outset and displaying an organisation and intensity on defence that limited the Reds' options.
Giteau and Cooper traded two penalties between them before, Moore posted the game's opening five-pointer midway through the first half following a sniping run from Patrick Phibbs.
The Brumbies halfback combined with Vaea to put Moore over under the posts and Giteau added the extras.
As the half-time approached, the Brumbies held a handy 13-point lead. However the Reds went to the interval more upbeat when Lucas managed to reach out score for a 19-11 scoreline at the break.
Brumbies flanker Mitch Chapman made a mess of a certain try in the second half when he put a hand into touch as he crossed in the corner. It gave the Reds a glimmer of hope, but poor handling cost them in promising positions.
Cooper missed one but nailed another long range penalty to bring his team to within five points of their Australian counterparts. But the Brumbies had the last laugh with Giteau's penalty in extra time to rub further salt into the Reds' wounds.
Pens: Cooper 3
Pens: Giteau 5
Reds: 15 Ben Lucas, 14 Luke Morahan, 13 Anthony Faingaa, 12 Ben Tapuai, 11 Digby Ioane, 10 Quade Cooper, 9 Will Genia, 8 Radike Samo, 7 Ben Coridas, 6 Scott Higginbotham, 5 James Horwill (c), 4 Rob Simmons, 3 James Slipper, 2 Saia Faingaa, 1 Ben Daley.
Replacements: 16 James Hanson, 17 Greg Holmes, 18 Adam Wallace-Harrison, 19 Jake Schatz, 20 Ian Prior, 21 Will Chambers, 22 Dom Shipperley.
Brumbies: 15 Pat McCabe, 14 Henry Speight, 13 Tyrone Smith, 12 Christian Lealiifano, 11 Adam Ashley-Cooper, 10 Matt Giteau (c), 9 Patrick Phibbs, 8 Ita Vaea, 7 Julian Salvi, 6 Mitchell Chapman, 5 Mark Chisholm, 4 Ben Hand, 3 Ben Alexander, 2 Stephen Moore, 1 Jono Owen.
Replacements: 16 Anthony Hegarty, 17 Jerry Yanuyanutawa, 18 Peter Kimlin, 19 Henry Vanderglas , 20 Nic White, 21 Robbie Coleman, 22 Andrew Smith.