A 77th-minute penalty from Peter Grant saw the Stormers beat the Bulls 20 -17 in a hard-fought battle in Cape Town on Saturday.
After trailing 14-0 at half time, the Bulls launched a thrilling comeback to level the scores at 17-all with just twelve minutes left on the clock.
But it was not to be for the men in...pink...as a controversial scrum penalty in the dying moments handed victory and the tournament lead to the Stormers, who remain the only unbeaten side in the competition.
There is clearly no love lost between these sides and the ferocious battle was characterised by an abundance of needle and petty off-the-ball incidents.
The former champions will head back to Pretoria harbouring a number of regrets after outscoring their hosts two tries to one, but ultimately paying for their chronic indiscipline.
Despite the Bulls dominating the early stages in terms of both territory and possession, Stormers full-back Joe Pietersen was able to kick his team into a 6-0 lead by the half-hour mark.
The Bulls' indiscipline saw them fall further behind as Pietersen added a third penalty to extended the lead to nine points, despite the hosts having hardly visited the Bulls' 22.
When the Stormers did eventually threaten the whitewash on the stroke of half time, they made it count as Tiaan Liebenberg crashed over from short range after a powerful run from Siya Kolisi.
Pietersen's conversion was wide but the home side nevertheless held a 14-0 lead at the interval.
Things went from bad to worse for the Bulls after the break when Flip van der Merwe saw yellow for taking Eben Etzebeth out in the air at a line-out.
But the sin-bin period proved to be the Bulls most profitable period as first Bjorn Basson won a foot race to Francois Hougaard's chip ahead and then Morne Steyn reduced the gap to just four points from the kicking tee.
Pietersen restored the seven-point lead soon afterwards but the Bulls' comeback was relentless and Wynand Olivier made Andries Bekker pay for a defensive error to slip away and score in the corner.
Steyn's touchline conversion levelled matters in the 68th minute, setting up a grandstand finish.
But it would be Grant who had the last laugh, splitting the uprights with his first kick of the game to claim his side's fifth win of the season.
For the Stormers:
Pens: Pietersen 4, Grant
For the Bulls:
Tries: Basson, Olivier
Cons: Steyn 2
Yellow cards: Van der Merwe (Bulls - 42nd min - puling line-out jumper down)
Stormers: 15 Joe Pietersen, 14 Gio Aplon, 13 Juan de Jongh, 12 Jean de Villiers (c), 11 Bryan Habana, 10 Peter Grant, 9 Dewaldt Duvenage, 8 Duane Vermeulen, 7 Rynhardt Elstadt, 6 Siya Kolisi, 5 Andries Bekker, 4 Eben Etzebeth, 3 Brok Harris, 2 Tiaan Liebenberg, 1 Steven Kitshoff.
Replacements: 16 Deon Fourie, 17 Frans Malherbe, 18 De Kock Steenkamp, 19 Nic Koster, 20 Louis Schreuder, 21 Burton Francis, 22 Gerhard van den Heever.
Bulls: 15 Zane Kirchner, 14 Akona Ndungane, 13 Johann Sadie, 12 Wynand Olivier, 11 Bjorn Basson, 10 Morné Steyn, 9 Francois Hougaard, 8 Pierre Spies (c), 7 Jacques Potgieter, 6 CJ Stander, 5 Juandré Kruger, 4 Flip van der Merwe, 3 Werner Kruger, 2 Chiliboy Ralepelle, 1 Dean Greyling.
Replacements: 16 Bongi Mbonambi, 17 Frik Kirsten, 18 Wilhelm Steenkamp, 19 Arno Botha, 20 Jano Vermaak, 21 Louis Fouché, 22 JJ Engelbrecht.
Referee: Craig Joubert (South Africa)