Sydney - The Bulls ended the Waratahs' 11-match unbeaten home run with a convincing 20-6 victory in a Super 14 match on Saturday.
The 2007 champions scored the only tries of the match to nudge the Waratahs out of third spot on points differential after nine rounds.
The Bulls rebounded from losses in their opening two Australasian tour games to dominate the top-four showdown and improve their chances of hosting one of the two playoff games next month.
Tries to winger Bryan Habana and prop Werner Kruger and two conversions, a penalty and drop goal from flyhalf Morne Steyn were enough to end the Waratahs' Australian record-setting winning streak at home.
Former world player of the year Habana, scored his 31st Super rugby try in the 17th minute to send the Bulls on their way, carrying over two defenders after the Bulls' forwards had taken play close to the Waratahs' line.
Flyhalf Daniel Halangahu reduced the deficit to 7-3 at half-time with an penalty goal in stoppage time.
But the Bulls asserted control after the resumption with Steyn slotting a drop goal in the 45th minute followed by a penalty 10 minutes later to establish a 13-3 lead.
The Waratahs pulled back three points with a 56th-minute penalty from replacement flyhalf Kurtley Beale.
But the South Africans wrapped up the contest 12 minutes from the end when prop Kruger crashed over off a ruck, with Steyn adding the extras.
Must beat Force
"The win wasn't pretty, but we got the four points that we came here for," Bulls' skipper Victor Matfield said.
"It was all about pushing them into their half and keeping them there with a great defence and kicking game and I think that worked for us."
The comprehensive loss put renewed pressure on the Waratahs, who went try-less in a Super 14 game for the first time in two years and they must now beat the Western Force in next Saturday's Australian derby game in Sydney.
"It's such a fine line between winning and losing games and you have to be up for every game, and tonight we certainly weren't," said Waratahs' skipper Phil Waugh.
The Bulls stay in Australia, with a match against the Brumbies in Canberra on Friday.
Bulls: Tries: Bryan Habana, Werner Kruger; Conversions: Morne Steyn (2); Penalty: Steyn; Drop goal: Steyn.
Waratahs: Penalties: Daniel Halangahu, Kurtley Beale.