The Brumbies centre Tevita Kuridrani scored a last ditch try to sink the Bulls 26-23 in their Super Rugby semi-final at Loftus Versfeld to book a grand-final berth with the Chiefs in Hamilton.
It's the first time the Bulls have lost a Super Rugby finals match at their South African home.
The Bulls may be kicking themselves after turning down penalty goals on three occasions while one point up within 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 managed to obtain good territory off the resulting kick-off, flyhalf Matt Toomua busting the line in the 79th minute to send Kuridrani over next to the posts.
Two uncharacteristic goal-kicking misses from Bulls sharpshooter Morne Steyn early in the match also came back to haunt the home side.
Brumbies flanker George Smith was magnificent, menacing the Bulls at the breakdown and making a crucial try saving tackle minutes after half time.
The Brumbies completely outmuscled the Bulls' scrum to earn three kickable penalties,
Christian Lealiifano successfully slotting two of them.
BRUMBIES 26 (Tevita Kuridrani, Jesse Mogg tries Christian Leali'ifano 2 cons 4 pens) BULLS 23 (JJ Engelbrecht try Morne Steyn 6 pens)