The winners of 13 championships will fight out next weekend's Super 15 semi-finals after two-time winner ACT Brumbies squeezed through to the last four on Sunday.
Australia's Brumbies clung on for a 15-13 victory after a sideline conversion attempt by Central Cheetahs fly-half Riaan Smit hit an upright after the full-time siren in Canberra, while the seven-time champions Canterbury Crusaders dominated the Queensland Reds 38-9 in the other qualifier in Christchurch on Saturday.
The Brumbies, winners in 2001 and 2004, will have to make the long trip to take on triple champions Northern Bulls in Pretoria next Saturday, while holders Waikato Chiefs host the Crusaders in the other all-New Zealand semi-final in Hamilton.
The Cheetahs came desperately close to taking the Canberra playoff into extra time when substitute winger Rayno Benjamin crossed in the left corner, giving Smit a kick from the sideline to level the scores after the full-time siren.
But Smit's kick swerved into the left upright to end the Cheetahs' Super 15 campaign, while the Brumbies lived on to fight for another week.
It was further heartbreak for the Bloemfontein-based Cheetahs, who have still to win after six trips to Canberra, but they have lost their last two games in the national capital by a point and now two points.
The Cheetahs scored the only tries of a gruelling battle through centre Johann Sadie and Benjamin, while Smit landed just one penalty from four kicks at goal.
The Brumbies' points all came from penalties, with Wallaby back Christian Lealiifano landing four from six and scrum-half Nic White succeeding with a long-range attempt.
Meanwhile, the formidable Crusaders stormed into the last four with a commanding four-try victory over the 2011 winners Queensland Reds.
The Crusaders, with All Blacks skipper Richie McCaw returning from a rugby sabbatical for his first game of the season, scored two tries in each half as they stepped up their drive for an eighth Super crown and shattered the Reds hopes of a second.
They made no secret in the build up to the game they were still hurting from their 18-13 final defeat to the Reds two years ago and their determination for revenge was evident from the start.
Their all-All Blacks forward pack gained dominance early in the set piece, holes were found in the Reds midfield and a blitz opening had the Crusaders up 10-0 within 10 minutes.
The expected showdown between fly-halves and likely Test rivals Daniel Carter and Quade Cooper was a non event.
Carter was the maestro conductor who dictated the direction of the frantic-paced Crusaders game, while Cooper was content to play a distributor's role and seldom took on the gain line.
It has been 14 years since the Reds last won in Christchurch and their chances of arresting that losing streak looked remote from the opening minute.