The Brumbies secured only a second win for an Australian franchise in Super Rugby Trans-Tasman, stunning the Hurricanes.
The Chiefs did their best to produce a stunning comeback, but the Reds held on to secure a hard-fought victory.
Richie Mo'unga shone as the Crusaders, winners of Super Rugby Aotearoa, thrashed Australian champions the Reds in their Trans Tasman clash.
Both New Zealand franchises were victorious when Super Rugby Trans-Tasman started in entertaining fashion.
Saturday's defeat left the Waratahs with a 0-8 record in Super Rugby AU this season.
A thrilling contest between Western Force and Waratahs was settled in the hosts' favour when Domingo Miotti struck late on.
A Super Rugby loss came as a significant shock to the Crusaders, but it was a familiar feeling for Waratahs as they fell short again.
Alex Mafi crossed three times as the Reds thrashed Waratahs on Saturday, while the Chiefs edged out the Blues late on.
The Waratahs left their rally far too late in a fourth straight defeat on Friday, losing to a Rebels team inspired by Matt Toomua.
The Rebels could not make their man advantage count as Ryan Lonergan's heroics off the bench sealed victory for the Super Rugby AU leaders.