The Blues played the spoiling role to perfection in robbing the Brumbies of a Super Rugby finals berth after they led the Australian conference for all but the last day of the last round.
The Brumbies were knocked out of the top six with the Queensland Reds, Sharks and Bulls all pulling off last-round bonus-point wins after the ACT franchise opened the door by stumbling against the lowly Blues.
The Aucklanders, who managed just four wins from 16 starts this season, scored a shock 30-16 win in Canberra when the Brumbies only needed to lose by less than seven to book a first play-off spot since 2004.
The team guided by 2007 World Cup-winning South Africa coach Jake White finished equal on points with the Reds (58) but gave up top spot on the national conference because Queensland won more matches, 11 to 10.
The Bulls ultimately left the Brumbies heart-broken by defeating fellow South Africans the Lions 37-20 in chilly Pretoria on Sunday morning (NZT), after being held 20-20 at halftime.
The Sharks had earlier jumped into the top six with a come-from-behind 34-15 win over the Cheetahs in Durban.
They scored four second-half tries after trailing 15-6, dashing any Hurricanes' hopes of making the playoffs after their upset 28-25 win over the Chiefs in Wellington on Friday.
Defending champions Queensland will now host the Sharks at Suncorp Stadium on Saturday night, while the Bulls make the long trip to Christchurch to play the Crusaders, who beat the Western Force 38-24 in Christchurch on Saturday.
The table-topping Stormers, who sealed top spot with a 26-21 win over the Rebels, and runners-up the Chiefs receive byes into the semi-finals and will enjoy home advantage in Cape Town and Hamilton respectively.