The Hurricanes booked their place in the Super Rugby play-offs with a hard-fought 28-17 victory over the Waratahs, who now face an uphill task to extend their season.
Daryl Gibson's men had the opportunity to leapfrog the Brumbies at the top of the Australian Conference on Saturday by claiming just a losing bonus point, but were unable to do so despite initially fighting back from 11 points down to lead.
The Tahs therefore remain behind the Brumbies on games won and face a daunting trip to Auckland to face the Blues in the final round, while their rivals take on struggling Western Force.
Defeat for the Waratahs also means the Highlanders can secure a play-off berth with victory over the Jaguares later on Saturday.
Beauden Barrett was typically influential in Sydney and, after landing two early penalties, the fly-half collected a chip over the top from Cory Jane to score his side's first try.
The Waratahs responded strongly, Taqele Naiyaravoro and Israel Folau each crossing the whitewash either side of half-time, the latter with the visitors' Willis Halaholo in the sin bin for a high tackle.
However, a converted score from Jane put the Hurricanes back in front and Julian Savea added a crucial third try after Naiyaravoro had been yellow carded for tackling Barrett in the air.
Naiyaravoro almost scored in the left corner on his return, but the impressive Barrett got across to make a try-saving tackle.