The Brumbies have stunned the Chiefs 26-14, putting a week of health uncertainty behind them in an emphatic trans-Tasman Super Rugby boilover.
In a clash of two conference-leading teams, the Brumbies played one of their most compelling halves of rugby in Hamilton on Saturday to lead 19-0 at the break, before repelling the home side's threat of a comeback.
The Brumbies hadn't won in New Zealand since 2014 - and not in Hamilton since 2007 - but played inspired rugby from the outset, running in a fourth unanswered try early in the second half to go 26 points clear.
Two quickfire tries got the Chiefs back in contention with 25 minutes still to play but they couldn't cross again, handing them a first loss under new coach Warren Gatland.
Having suffered a last-gasp loss to the Highlanders last week, the Brumbies defended with desperation, shutting down a host of late attacks.
The Canberra side's performance was all the more remarkable given a mumps outbreak that struck the Brumbies about 10 days ago, rendering some squad members unable to make the trans-Tasman trip.
It seemed to unite the players, who dominated the early physical exchanges on the back of their Wallabies props Allan Alaalatoa and James Slipper and some powerful work from young flanker Rob Valetini and centre Tevita Kuridrani.
Rookie five-eighth Noah Lolesio threw a handful of expert offloads to create space and lively fullback Tom Banks was a beneficiary with the opening try.
Quick hands from Banks set up winger Solomone Kata soon afterwards before a try-scoring double to standout No.8 Pete Samu either side of halftime.
The first came through a dominant scrum and the second via the back-rower's athleticism, slicing past three tacklers on a 30m run.
Starved of ball, the flustered Chiefs spilled possession and fell off tackles.