Berrick Barnes broke the back of the Brumbies as the Waratahs won 28-22 in Sydney.
The Brumbies led 13-6 at halftime and, despite losing a man to the bin on 50 minutes, led 22-19 with 20 to play.
But, as he did a week ago against the Stormers, Barnes produced a moment that gave the Waratahs momentum and ultimately the match.
The Tahs replacement flyhalf, being nursed back to the run-on XV after two months out of the game, excelled in the last 30 minutes. He showed excellent decision-making and control and scored the try that reduced the deficit to just one point.
Winger Peter Betham then put the Tahs ahead with three minutes to play and the Brumbies so nearly stole the result in the final minute. The Brumbies maul was held up just short of the Tahs line and the hosts won a turnover scrum. It proved to be the final act of the game.
The Wallabies 25-strong squad gets announced on Sunday and several players impressed. Brumbies fullback Jesse Mogg was the pick of the backs and Michael Hooper was as good as George Smith. Ben Mowen also played well against his former teammates but not well enough to prevent a first loss in four starts.
The Brumbies hammered the Tahs in the early season fixture.
Waratahs – Tries: Michael Hooper, Berrick Barnes, Peter Betham. Conversions: Barnes (2). Penalties: Brendan McKibbin (2), Barnes.
Brumbies – Tries: Ben Mowen, Tevita Kuridrani. Penalties: Christian Lealiifano, Jesse Mogg (3).