The Bulls extended their winning streak over the Waratahs to eight consecutive matches when they beat the men from Sydney 30-19 at Loftus Versfeld.
The result puts the Bulls back into the top three after the Sharks had moved to the top of the South African Conference earlier in the round.
The Bulls were outscored by two tries to three with man of the match Morne Steyn scoring a try, six penalties and a conversion.
The final score does not indicate how closely the Waratahs pushed the Bulls as man of the match Morne Steyn scored a try on full time after the Waratahs had been trailing and pushing hard at 25-19.
The Bulls were made to work for the victory as the Waratahs pressure meant the home side struggled to find the fluency needed to dominate proceedings.
The Bulls led 12-5 at the break after both sides struggled to find holes in the opposition's defence but the Waratahs took the one chance they were given to score a try.
Steyn gave the Bulls a nine-point cushion after a half hour of play in the first half having succeeded with three penalty conversions.
The Waratahs had little possession or room to manoeuvre but, nevertheless, grabbed the points on offer.
The hosts slowly chipped away at the Waratahs' morale with Steyn jogging back with three points in the bag after every penalty attempt.
The tourists, however, foud their way over the whitewash six minutes from the break to keep the Loftus faithful on the edge of their seats.
The Bulls defence was found wanting as sensational Waratahs fullback Israel Folau beat both winger Akona Ndungane and fullback Ulrich Beyers to the line.
Waratahs scrumhalf Brendan McKibbin failed to convert the try, while Steyn succeeded with another penalty on the half-time whistle, to give his team the seven-point lead.
The Australian franchise were given another scoring opportunity on a silver platter as a lapse in defence saw replacement prop Paddy Ryan score for the Waratahs.
The Bulls looked dangerous on attack until Folau intercepted a Steyn pass to advance to the other side of the field.
With the Bulls defence in disarray, McKibbin offloaded to Bernard Foley, who scored his side's second try of the evening to hand them a 19-15 lead with 20 minutes left in the match.
Replacement scrumhalf Francois Hougaard, however, put his side back into the lead as he picked up a ball from the ruck, just metres from the line to score, with Steyn converting.
Steyn then wrapped up proceedings converting another penalty and scored a try at the death.
The Waratahs have not beaten the Bulls since 2005 and their last victory at Loftus Versfeld was in 2002.
Final Score Bulls 30 (12) Waratahs 19 (5)
Tries - F,Hougaard, M Steyn
Pen - M.Steyn 6
Con - M.Steyn
Tries - I.Folau, P.Ryan, B.Foley
Con - B.McKibbin 2
Referee: Francisco Pastrana
Assistant Ref 1:Sindile Mayende
Assistant Ref 2:Ben Crouse
TMO : Gerrie Coetzee
Ulrich Beyers , Akona Ndungane, JJ Engelbrecht, Jan Serfontein, Bjorn Basson, Morne Steyn, Jano Vermaak, Pierre Spies (c), Arno Botha, Dewald Potgieter , Juandre Kruger, Flip van der Merwe, Werner Kruger, Chiliboy Ralepelle, Dean Greyling
Replacements: Willie Wepener, Hencus van Wyk , Wilhelm Steenkamp, Jacques Potgieter , Francois Hougaard , Louis Fouche, Lionel Mapoe.
1. Benn Robinson , 2. Tatafu Polota-Nau , 3. Sekope Kepu , 4. Sitaleki Timani , 5. Kane Douglas , 6. Dave Dennis (c) 7. Michael Hooper , 8. Wycliff Palu , 9. Brendan McKibbin , 10. Bernard Foley , 11. Tom Kingston , 12. Rob Horne , 13. Adam Ashley-Cooper , 14. Cam Crawford , 15. Israel Folau
Replacements 16. John Ulugia , 17. Paddy Ryan , 18. Mitchell Chapman , 19. Pat McCutcheon , 20. Matt Lucas , 21. Ben Volavola , 22. Peter Betham