The Bulls' hopes of defending their title were given a welcome boost with a 23-17 win over the Waratahs that extended their unbeaten run to five.
After a stuttering start, the Bulls have found their feet over recent weeks and this win means they have leapfrogged the Sydney side into the Super Rugby play-off positions.
The Waratahs drew first blood with a third-minute Kurtlet Beale penalty from 45 metres out, and the same player blew a chance of further points shortly after when he overshot the line as he ran at the home defence.
The Waratahs were playing with a purpose and Berrick Barnes went close with a dropped goal attempt, only for their hard work to be pegged back by a Morne Steyn penalty after 15 minutes.
Tatafu Polota-Nau broke through the home defence and was set to score until a try-saving tackle from full-back Zane Kirchner, but Beale kicked another penalty shortly after to regain the lead.
The play was flying from end to end, albeit without a cutting edge, before Steyn levelled things with a penalty after the Waratahs failed to bind at the scrum.
Steyn then missed another penalty that would have given his side the lead, but they managed to take it into the half-time interval anyway.
With a minute remaining, Gerhard van den Heever passed to Wynand Oliver from the lineout and he did the rest, with Steyn converting.
Having stung their opponents with a late try in the first half, the Bulls went over for an early one in the second, with Kirchner's strong running allowing Bjorn Basson to race clear and equal Bryan Habana's record for the most tries in a Super Rugby season with his ninth effort of the year.
Steyn landed the conversion and the Waratahs suffered another blow when Ben Mowen limped off with an injury.
Beale landed a penalty to ease their worries, and they were right back in the game when Barnes put Atieli Pakalani over for a try.
Beale missed the conversion but of more concern to the the Waratahs was Pat O'Connor's sending-off for an alleged headbutt with 13 minutes remaining.
Steyn slotted the subsequent penalty and then hit the post with another, before a stunning tackle from Chiliboy Ralepelle stopped Beale from potentially setting up victory for his side with a try three minutes from time.
Scorers were:
Bulls 23
Tries: Basson, Olivier
Con: Steyn 2
Pen: Steyn 3
Waratahs 17
Try: Pakalini
Pen: Beale 4
HT: 13-6