Marcell Coetzee emerged as Ulster's chief tormentor by blasting over for the crucial try against his old team-mates as the Vodacom Bulls ran out 34-16 winners in Pretoria.
Few thrills were produced in a first half dominated by the defences and the whistle of referee Andrea Piardi that allowed Nathan Doak to kick the Irish province into a 9-3 interval lead.
But in 25-degree heat at Loftus Versfeld, the Bulls then ignited, with powerful flanker Coetzee crossing in the 44th minute to wrestle the advantage away from Ulster before Madosh Tambwe, Johan Grobbelaar and Kurt-Lee Arendse added further tries to complete a bonus-point victory.
A late yellow card for a dangerous tackle cast a minor shadow on Coetzee's afternoon, but he had already left his mark on the side where he spent five seasons until 2021.
Ulster lost wing Ethan McIlroy in the third minute after he took an elbow to the head from Tambwe as the rivals contested for an aerial ball, but it failed to dent a strong start from the visitors.
A Doak penalty was the only reward for their early dominance and the Bulls soon forced their way back into contention with Chris Smith levelling from the kicking tee.
Defences reigned in an increasingly hard-fought first half that saw regular intervention from Piardi and, with the Bulls coming off worse, Doak was able to boot another six points.
Only last-ditch intervention from Ian Madigan prevented Tambwe from crossing in the left corner, but where the backs failed the forwards succeeded when a series of pick-and-goes produced a try for Coetzee as the lead changed hands for the first time.
Pressure was building on Ulster with Coetzee a force in the forward exchanges and, when Smith kicked the Bulls 13-9 ahead, the tide had turned.
Tambwe showed strength to score his side's second try born out of an error in the visitors' midfield, but Marshall went over with 15 minutes to go after brave approach work from Madigan to hint at an uprising.
Any comeback aspirations soon vanished, however, when lock Kieran Treadwell was sin-binned for a dangerous tackle and Bulls surged over with a maul try from hooker Grobbelaar.
Arendse completed the rout by picking off a loose Ulster pass, sealing an emphatic win.