The Brumbies have claimed Super Rugby bragging rights over arch-rivals the Waratahs, hanging on for a thrilling 19-13 upset victory at GIO Stadium.

Entering the Australian conference derby on Friday night after two straight defeats, the ACT franchise were inspired thanks to a double from hooker Folau Fainga'a.

There were some anxious moments for the Brumbies late in the match as the Waratahs did most of the attacking in the last 20 minutes, but the home side did enough in front of 12,112 fans.

The Brumbies' second win of the season came in spite of a disastrous start where the Waratahs opened the scoring in bizarre circumstances after five minutes.

Waratahs flyhalf Bernard Foley slammed a straight-forward penalty attempt straight into the post, before captain Michael Hooper pounced on a loose ball for the first try of the match.

But rather than go into their shells following some lacklustre defence, the Brumbies responded by dominating the rest of the first half.

Fainga'a strengthened his Wallabies credentials by crossing the line twice to become the first Brumby since Andrew Walker in 2004 to score a try in five consecutive games.

The Waratahs' cause wasn't helped when prop Sekope Kepu was sent to the sin-bin just before halftime for a high shot on Brumbies No. 8 Lachlan McCaffrey

Waratahs winger Alex Newsome cut the Brumbies 12-5 halftime lead to only two points when he crossed early in the second half.

But the Brumbies received a penalty try a few minutes later, with the Waratahs having another player go to the sin-bin when Harry Johnson-Holmes was sent off.

The Brumbies' horror luck with injuries continued as star prop Scott Sio (arm) and flanker Rob Valetini failing to finish the game.