The Stormers remain the only unbeaten team in the Super 15 series after a gripping 20-17 derby win over the Bulls this weekend.
The Cape Town-based Stormers, New Zealand's Otago Highlanders and the ACT Brumbies of Australia are leaders of their national conferences after six rounds of the southern hemisphere provincial championship.
The Highlanders made it five wins from six outings with a seven-try blitz to trounce the Melbourne Rebels 43-12 in Invercargill, while the Brumbies held on to the lead in the Australia conference despite going down 29-26 to the Coastal Sharks in Canberra.
The Waikato Chiefs joined the Highlanders on level points in the New Zealand conference with their comprehensive 30-13 win over the New South Wales Waratahs in Hamilton.
All Blacks ace Dan Carter had a quiet opening game of the season as the Canterbury Crusaders downed the Golden Lions 23-13 in Johannesburg.
South Africa's Central Cheetahs beat the Hurricanes 47-38 in a helter-skelter encounter that produced 10 tries in Wellington.
Faltering defending champions Queensland Reds slumped to their third straight defeat in a 45-19 loss to the Western Force in Perth and have now conceded 106 points in their past two games.
At Newlands, a penalty three minutes from time by fly-half Peter Grant got the Stormers home against the three-time champion Bulls.
But the Bulls were the dominant team in the second half of a ferociously contested match, fighting back from a 14-point deficit to level at 17-17 with 13 minutes to go.
The Bulls scored two tries to one by the Stormers, but full-back Joe Pietersen landed all four penalty attempts and Grant succeeded with his only shot at goal.
The Highlanders returned to winning ways after suffering last week's first loss of the season to the Brumbies. They cut loose in the second half against the Rebels after it was 12-12 at half-time.
The Rebels were beaten for the fourth time in five games.
The Sharks held off the Brumbies 29-26 for their first Super Rugby win in Canberra in 14 years.
The Durban-based Sharks clinically took their chances to seize a four-try bonus point and their third win of the Super 15 season.
They had to withstand a storming finish from the Brumbies, who crossed for a converted try in the 79th minute to set up a furious finale that saw them get within 30 metres of the Sharks' try-line before play broke down.
In Hamilton, the Waratahs had most of the first-half possession, but after the interval the Chiefs outscored the Sydneysiders 17-3.
At Ellis Park, Carter ceded the place-kicking duties to inside-centre Tom Taylor, who succeeded with five of six shots at goal.
But Carter, sidelined by a groin injury during the triumphant march of New Zealand to the World Cup title last October, played a role in both Crusaders' tries.
In Wellington, both the Cheetahs and Hurricanes had a four-try bonus point by halftime, but as the game progressed the Cheetahs' forward power made the difference.
The Reds were never in the contest in Perth, as the Force dominated the early stages to ensure Queensland could not build back any confidence after their mauling by the Bulls in Pretoria the previous weekend. – Sapa-AFP