Noah Lolesio returned from two months out with a torn hamstring to inspire the Brumbies to glory over the Reds in the Super Rugby AU final.
The Brumbies will host the Reds in the Super Rugby AU final next weekend after Brad Thorn's team overcame the Rebels on Saturday.
James O'Connor scored a try and kicked 17 points as the Reds achieved a record win over Western Force on Friday.
The Reds came from behind to claim a bonus-point victory against a wasteful Rebels in Saturday's Super Rugby AU clash.
The Waratahs scored 38 points without reply in the first half as they cut loose in the rain to thrash the Reds in Sydney.
The Brumbies were victorious once again in Super Rugby AU, though left it late to see off the Reds in Canberra.
The Reds made it two Super Rugby AU wins out of three, but they were pushed all the way by the Western Force.
Bryce Hegarty came close to sealing the first ever Super Time victory but it was honours even at Brookvale Oval.
The scores were level in the closing stages at Suncorp Stadium, but James O'Connor's penalties saw the Reds past the Waratahs.
Lyon have confirmed the signing of towering lock Izack Rodda, who refused to take a pay cut to remain in his homeland.