Wellington - South African teams occupy three of the top six places in the Super Rugby competition after the weekend's 12th round as the playoff campaigns of New Zealand and Australian teams began to falter.
The Bulls, Stormers and Sharks were all 12th-round winners, consolidating their places among the top six teams which will contest the playoffs later this season.
The Bulls' 27-24 win over the Waratahs took them to the top of the standings. They maintained a one-point lead over the Chiefs, who lost 42-27 to the defending champions, the Reds, on Sunday.
The Stormers' 16-14 win over the Cheetahs and the Sharks' 53-11 win over the Force left them in fourth and sixth places respectively.
The Crusaders held onto fifth place despite a 28-19 loss to the Rebels, which was still a setback to their playoff bid. It ended a four-match streak which included wins over the Stormers and Reds.
The Highlanders were beaten 26-20 by the Hurricanes, falling back to seventh place as their second straight loss undermined their best start to a Super Rugby season.
The Higlanders remain only a point outside the top six and the Hurricanes, with their sixth win from 11 games, are a further point back and still on the fringes of playoff contention. Pressure on teams to repair faltering campaigns will increase as the tournament heads towards a break for June Test matches.
The Bulls took a giant stride towards the playoffs and their fourth Super Rugby title with a win over the Waratahs that kept them at the top of the South African conference, a point ahead of the Stormers.
The win was their fifth in succession, improved their record to 8-2 and firmly dispelled suggestions their loss of senior players at the end of last season significantly diminished their strength. They beat the Waratahs for the seventh straight time, clinching the win with a try to prop Werner Kruger three minutes from full-time.
The Waratahs now face two matches in South Africa, against the Cheetahs and Stormers, but coach Michael Foley refused to concede his team's playoff ambitions were over.
"We'll chase every point there is to be had right until the last game of the year," Foley said. "I've been in some pretty weird situations leading into the end and missed out and there's been other teams that have just somehow made it, so we've got to give ourselves every possible chance.
"For us South Africa's massive. We need to come away from hopefully 10 points. If we don't come away with points, you can bet it's over."
Rebels scrumhalf Nick Phipps scored two tries and 35-year-old former Wallabies captain Stirling Mortlock added another as the Rebels posted their first-ever win over the Crusaders. The Crusaders' loss was made more costly by a hip injury to All Blacks backrower Keiran Read.
"It was frustrating ... we were in control of the game but we lacked urgency and then we gave away some silly, dumb penalties," Crusaders coach Todd Blackadder said. "We allowed them back into the game through silly mistakes."
All Blacks captain Richie McCaw, who started a game for the first time this season, said his team needed to start better.
"They're a team that needs to start well and we allowed them to do that," he said. "The first 20 minutes, they came out and played well and also defended pretty well. They grew an arm and a leg as the match wore on."
The Stormers scored 16 unanswered points in the first half, then had to hold off a spirited second-half charge from the Cheetahs to improve their record to 9-1.
"It wasn't good, and if we want to play like this then I can't see us going much further in this competition," returning Stormers captain Jean de Villers said.
Two breakaway tries early in the second half by winger Lwazi Mvovo led the Sharks to their big win over the Force.
Steven Sykes, Paul Jordaan, Louis Ludik, Craig Burden, Jacques Botes and Mvovo all scored tries as the Sharks notched a fifth straight win.