The Waratahs closed the gap on the Brumbies to one point after they battled past their Australian conference rivals 13-10 in Canberra on Friday.
Victory is the Sydney side's fourth straight over the Brumbies as they have put a great deal of pressure on Stephen Larkham's charges, who now travel to South Africa to kick-off their difficult tour period against the Stormers at Newlands.
The 'Tahs meanwhile head to Perth to face the Force with their tails up.
The Brumbies emerged with real intent and opened the scoring in the seventh minute when a lovely looped pass from centre Robbie Coleman out to left wing Joe Tomane saw him go over for the first points. Fly-half Christian Lealiifano fired over the difficult extras to make it 0-7.
However, the Waratahs soon settled and landed a response of their own six minutes later when Benn Robinson's carry to within a metre of the line led to scrum-half Nick Phipps sending out a Coleman-esque pass to centre Adam Ashley-Cooper for the try. Bernard Foley kicked the two.
Australia's openside battle for the Rugby World Cup was the major subplot of this Super Rugby derby fixture and the duo did not disappoint early on as Michael Hooper put in a big hit on powerful Brumbies number eight Ita Vaea while David Pocock was a nuisance at the breakdown. But what will worry Wallaby head coach Michael Cheika somewhat was that hooker Tatafu Polota-Nau left the action early on with another concussion.
Mistakes from both sides hampered the second quarter of the derby game as handling errors were prominent despite the favourable conditions.
Lealiifano missed a penalty on 24 minutes but was on-target soon after to make it 7-10, with Foley also wayward five minutes from the break. And that was how things remained in Canberra with the Brumbies going into the interval the happier side due to the 'Tahs sloppy tendencies.
Cheika's words clearly had some effect at the turnaround as his men went close to scoring soon after the break as Kurtley Beale's grubber kick down the line led to a foot race to the ball. Fortunately for the Brumbies, Jesse Mogg was first to arrive and dot down in his in-goal area.
Their improvements were rewarded soon after with a levelling three points via the boot of Beale as prop Ben Alexander was pinged at a ruck.
Cheika clearly sensed his side was gaining the upper hand and sent on the powerful Taqele Naiyaravoro in place of Peter Betham on 50 minutes. He also brought off number eight Wycliff Palu as Stephen Hoiles emerged in a game that looked set to go right down to the wire.
On 58 minutes the Waratahs would lead for the first time as Foley slotted three points after Vaea had been caught offside at the breakdown.
Their advantage didn't look like lasting too long though as with Rob Horne in the sin-bin for an offside offence at the maul, the Brumbies enjoyed 92 percent of possession in a five minute spell after the hour. Somehow the Waratahs survived a barrage on their line.
Strangely the Brumbies then snubbed a shot at three points from 40 metres out with time almost up that would have levelled the scores, instead going for the corner. And it backfired as the 'Tahs held on thanks to Robinson's turnover in their 22 to claim a priceless victory.