The Brumbies have won through to their first Super Rugby final in nine years after centre Tevita Kuridrani scored a last ditch try to sink the Bulls 26-23 in Pretoria.
It's the first time the Bulls have lost a Super Rugby finals match at their South African home.
The Bulls turned down three penalty goals to kick for the corner while one point up in the final 13 minutes as the Brumbies' staunch defence held them out.
It took a message from Bulls coach Frans Ludeke to take the three points when they were offered for a fourth time in the 76th minute.
However the Brumbies obtained good territory off the resulting kick-off and flyhalf Matt Toomua busted the line to send Kuridrani over in the 79th minute, TMO Shaun Veldsman ruling there was no forward pass in the lead up.
Bulls captain Dewald Potgieter defended his decision to turn down the three penalty goal attempts.
"We tried to spend most of the time in their territory and it was working for us right up until the end when we took that penalty and were back in our own half," he said.
"We were struggling all night with our exits.
"Probably not always the popular choice (to turn down three points) but you've got to back what you want to do."
Brumbies captain Ben Mowen praised his men for their brilliant defence when the Bulls were dominating both territory and possession late in the game.
"Momentum comes and goes in games and you've just got to make sure that when it is against you it's not costing you on the scoreboard," he said.
"The Bulls have got an outstanding rolling maul. We scrambled so well off our lineout defence inside our 22-metres five or six times there."
Brumbies flanker George Smith was magnificent with another man-of-the-match performance, menacing the Bulls at the breakdown and making an extraordinary try-saving tackle minutes after half time.
A penalty goal to Lealiifano opened the scoring in the third minute, winger Henry Speight then sensationally fending off three Bulls before flick passing to Mogg to extend the lead to 10-0.
But the Bulls hit back when centre JJ Engelbrecht gave Speight a taste of his own medicine to reduce the deficit to 10-5 in the 16th minute .
The teams traded penalty goals throughout until Kuridrani finished off an unlikely match winner to book a finals berth against the Chiefs in Hamilton next Saturday.
The Chiefs beat fellow New Zealanders the Crusaders 20-19 last night, a result similar to last year's 20-17 win over the same opponents in the same fixture.
ACT Brumbies 26 (Tevita Kuridrani, Jesse Mogg tries Christian Leali'ifano 2 cons 4 pens) Bulls 23 (JJ Engelbrecht try Morne Steyn 6 pens) at Loftus Versfeld. Referee: Craig Joubert
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