The Brumbies have withstood a second-half onslaught by a transformed Queensland pack to put the Reds' Super Rugby finals hopes on the brink.
In a typically rugged Macqueen Cup battle, the Brumbies consolidated their lead at the top of the Australian conference with a tense 23-20 victory at Suncorp Stadium on Friday night.
It was the Reds' third loss this season by three points and has them 11th - nine points behind the ACT side - and slipping out of play-off contention heading into next week's bye.
Showing their slide, the defeat was their first back-to-back home loss since the dark days of 2009.
"It's just not good enough," said captain James Horwill.
In a topsy-turvy clash where the Brumbies dominated the first half, before the Reds pack - boosted by the injection of 100-gamer Saia Fainga'a - turned the tables in the second.
The astonishing set-piece turnaround was highlighted by a remarkable pushover try to Eddie Quirk from a tight-head scrum win in the 63rd minute that sparked the Reds revival and set up a tense finish.
Quirk's first Super try came 10 minutes after he was clocked by Stephen Moore just before Will Genia claimed a try in the corner.
In a controversial call that incensed the 30,004-strong Brisbane crowd, referee Steve Walsh disallowed the try because Quirk held Moore at the ruck on the goalline.
Quade Cooper, who endured a forgettable first half and dropped the ball over the line in the second, slotted a penalty goal to close the gap to three but that's as close as the Reds got.
"I thought the way we defended there in the second 20 minutes of the second half was magnificent and got us the result," said Brumbies skipper Ben Mowen.
The Brumbies were far slicker, faster and smarter in the first half and went into the sheds at 20-10 but were kicking themselves the lead wasn't 20-plus.
They regularly let the listless Reds off the hook with fumbles and forward passes when in the clear.
Queensland shot themselves in the foot from the outset with Cooper gifting Scott Fardy the opening try after Robbie Coleman jolted the ball free.
With their pack more efficient and the ball coming quickly from the breakdown, the Brumbies were far more organised and creative than the home side.
The pressure eventually told when slick hands from Nick White and Jesse Mogg - the two players the Reds targeted pre-match - finally made the most of an overlap for Joe Tomane to cross for a 20-3 lead.
Queensland's only joy came from a driving maul try to Beau Robinson which kept them in the game at halftime.
ACT Brumbies 23 (Scott Fardy, Joe Tomane tries Nic White 2 cons 3 pens) Queensland Reds 20 (Ed Quirk, Beau Robinson tries Quade Cooper 2 cons 2 pens) at Suncorp Stadium. Referee: Steve R. Walsh. Crowd: 30,004
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