Winger Joseph Tomane's three tries, Christian Lealiifano's sideline conversions, the hoodoo-breaking win at Allianz Stadium and the desperate defence. It was all done with Vaea firmly at the front of their minds after he was forced to retire last week.

The Brumbies beat the Waratahs 26-20 to end a four-year drought in Sydney and win at Allianz Stadium for the first time since 2002 in a huge result for the club at the start of a season-defining six-week block.

It came days after an emotional Vaea stood up in front of his teammates and told them a life-threatening heart condition had forced him to quit the game.

There were plenty of tears. But rather than dwell on the heartbreaking moment, the Brumbies responded in a way that fittingly paid tribute to Vaea's rugged style and brutal rugby mentality.

Tomane declared after the match: "If you're watching, brother I love you" after writing Vaea's nickname, "Dox", on his wrist for the stunning three-try performance.

Brumbies skipper Stephen Moore said Vaea's injury reminded everyone in the team that "you don't know when you've played your last game".

Moore also spent part of the Brumbies' bye week visiting former Maitland hooker Dom Punch, who suffered spinal damage in a game last year.

"We spoke about [Ita] before the game and a lot of the boys are very close to Ita, that was a big shock to us earlier in the week," Moore said.

"We did speak about the fact he can't ever play footy again, maybe that motivated us a bit. We'll make sure we support Ita as much as we can going forward, it's not just about tonight. It's about us getting around him over the next few months and years because he'll need that.

"I'd like to think all of those kind of things puts it in perspective. I was in Newcastle last week and saw a young fella who broke his neck playing rugby in Maitland and he's in a wheelchair for the rest of his life.

"That sort of stuff puts everything in perspective. It's only a game at the end of the day."

Tomane's three-try effort helped lift the Brumbies to a massive win against arch rivals the Waratahs, but the victory was built in desperate defence in the final stages as the NSW side launched wave after wave of attack.

Brumbies coach Stephen Larkham singled out replacement lock Tom Staniforth for throwing himself around the field as the Brumbies clung on to a late lead to inflict pain on the Waratahs' stuttering season.

Tomane has two tries in the first 15 minutes and the Brumbies looked as if they'd run away with the contest early, but the Waratahs found top gear and got themselves into the game.

They hit back first through former Canberra Raider Reece Robinson and then superstar Israel Folau, who bounced back from an early head knock to bamboozle the defence.

But the Waratahs have been their own worst enemies this year and their slender lead lasted just two minutes following an error after Folau's try, opening the door for the Brumbies to strike and Moore took advantage from the back of a rolling maul.

Tomane completed his hat-trick after half-time before the game descended into a slog, with the Brumbies scraping and fighting to hold on and the Waratahs searching for the game-turning try.

"We've always struggled to win up here, but tonight we won and not only that, we played well," Larkham said.

"We're worried in every second half. They threw a fair bit at us, particularly in that last bit but the boys were phenomenal defensively. The guys who came off the bench were superb, to single one out was Tom Staniforth. The game at the end was all about defence and Tommy led the way."

The Brumbies made a mess of the breakdown despite the absence of Vaea and the suspended David Pocock, paving the way for disrupting the Waratahs' dangerous back line.

AT A GLANCE

ACT BRUMBIES 26 (Joseph Tomane 3, Stephen Moore tries; Christian Lealiifano 2 conversions) bt NSW WARATAHS 20 (Reece Robinson, Israel Folau tries; Bernard Foley 2 conversions, 2 penalties) at Allianz Stadium on Saturday night. Referee: Nick Briant. Crowd: 25,319.

* To donate to Dom Punch's recovery from a spinal injury, visit: http://punchingabovefordom.com.au/