The NSW Waratahs have secured a week off and a home semi-final with a 31-5 win over the Queensland Reds at Allianz Stadium.
Having won the Australian conference before kickoff due to the Brumbies' loss to the Crusaders earlier on Saturday night, the Waratahs needed to beat the Reds to eliminate the Cape Town-based Stormers from the top-two race.
Michael Cheika's side came into the match leading the Stormers by two points on the ladder and a loss against the Reds would have given the South Africans a shot at bumping them from second spot in their game against the Sharks in Durban on Sunday (AEST).
The Waratahs came to life in the second half after a dreadful opening 40 minutes, punctuated by penalties and errors, saw the home side leading 3-0.
The game opened up on 50 minutes following the sin-binning of Reds flanker Adam Thomson, with the Waratahs scoring a try soon after when skipper Dave Dennis crashed over for his first try of the season after a lovely inside ball from five-eighth Bernard Foley.
The reigning Super Rugby champions had another five-pointer soon after when Jacques Potgieter opened his account for the season.
Foley was again the provider soon after when he produced another nice inside ball to send replacement halfback Brendan McKibbin under the posts.
Popular replacement lock Dean Mumm then sent the crowd of 26,746 wild when he scored the final try of the game.
Mumm was playing his first game in Sydney after three years playing in England and crashed over from close range.
Quade Cooper scored a late consolation try when he regathered his grubbing kick to score in the corner.
The loss is sure to heap more pressure on Reds coach Richard Graham who lost James O'Connor and James Slipper to injury on a night the Reds said goodbye to stalwarts Will Genia and James Horwill, who will continue their careers overseas.
Cheika said the halftime talk was positive despite the scrappy opening to the game and going into the break with just a penalty goal on the board against the battling Reds.
"We just talked about trying to get a little bit more go forward, getting our runners into the game so we could open up some space," he said after the 300th match between the sides.
Graham was disappointed after being so close at the break and admitted Thomson's sin-binning was crucial.
"As soon as we got down to 14 men we were under pressure. They dumped two tries on us quickly when we were down to 14 and from there we were always under pressure," said the Reds coach.
Meanwhile, Kurtley Beale was a late withdrawal due to a quadriceps injury suffered at training but Cheika is hopeful it's nothing serious.
"He did it having a kick at goal, so it's a little strain. Could we have pushed? I don't know and we chose not to," he said.
The Waratahs will host their semi-final in two weeks against the highest-ranked winner from the two qualifying finals next weekend.
The fourth-ranked Highlanders host the Chiefs in Dunedin on Saturday afternoon, while the sixth-ranked Brumbies travel to Cape Town to face the Stormers on Sunday (AEST).