The Brumbies booked their place in the Super Rugby semi-finals with a 32-30 win over the Chiefs, who saw their reign as champions ended in Canberra.
The home side looked to be romping to victory as tries from Nic White, Robbie Coleman and Jesse Mogg saw them open up a 19-point advantage just before the break.
But the Chiefs responded through Bundee Aki, Tawera Kerr-Barlow and Tim Nanai-Williams to level the scores before Jarrad Butler had the Brumbies back in front.
Gareth Anscombe grabbed a late try back for the defending champions but the conversion was missed and the Brumbies held on for victory.
Aaron Cruden booted the Chiefs into an early lead but they suffered a blow when Nanai-Williams was sin-binned for not rolling away near his own line.
Just six minutes were on the clock when the hosts had the first try, winning their own lineout and mauling towards the line with White the man to break out and go over.
Christian Lealiifano booted the conversion and just three minutes later the Brumbies were over again.
White found Mogg who showed blistering pace to get through his prospective tacklers before passing to Coleman who showed similar fleet of foot to get over, taking two Chiefs with him.
Lealiifano once again added the extras and the Australian side had an 11-point lead.
The Brumbies had their third midway through the half as Ben Mowen shrugged off three defenders and found Mogg, who sneaked over in the corner, but Lealiifano could not extend the advantage.
The centre did slot a penalty soon after but the Chiefs responded with some good forward work and Aki went over with Cruden cutting the gap to 12 points at the interval.
Cruden and Lealiifano exchanged penalties early in the second half before Henry Speight was sin-binned for the Brumbies for cynically killing the ball.
The Chiefs took advantage straight away from the resulting scrum as they got the ball to the line and Kerr-Barlow stuck an arm out to score.
Cruden added the conversion and just five minutes later the Chiefs were level as Nanai-Williams went over after some good work through several phases.
Lealiifano then missed an easy penalty chance before the Brumbies had their noses in front again with a maul form a lineout allowing Butler to go over. This time the centre split the posts.
Anscombe touched down for the Chefs with three minutes remaining but Cruden missed the conversion and the Brumbies held on for a narrow win.