The Brumbies made it four successive Super Rugby wins since their opening-weekend defeat with a 25-15 triumph over the Stormers in Canberra - their first victory over the South African side since 2010.
Brumbies winger Robbie Coleman scored two tries, the second of which came after the Stormers had failed to control a speculative kick in what was the defining moment of the match.
The Brumbies were only leading 13-10 with just over an hour gone when Coleman chased a kick by captain Ben Mowen which the Stormers' defenders had left in hope it would either go out or over the goal line.
But the left winger pounced and capitalised on a golden opportunity to score.
The Brumbies pack then won a penalty try from an attacking scrum in the final minute to seal the victory.
Brumbies scrum-half Nic White, who missed three shots at goal in the second half, slotted two conversions and two penalties.
For the Stormers, who have now lost four of their five matches this season, number eight Duane Vermeulen managed a first-half try before replacement Juan de Jongh grabbed another with five minutes left.
Fly-half Peter Grant added the rest of their points from a conversion and penalty, but it was not enough to deny the home side.
The victory lifts the Brumbies to the top of the Australian conference on 17 points, one ahead of the Waratahs.