Janko became the first player to score in seven consecutive A-League games and went on to claim a hat-trick prior to a sensational conclusion to the game.
Sydney led 4-1 with 15 minutes remaining courtesy of Janko's third goal, but ended up holding on as Brisbane came roaring back late on.
Henrique had opened the scoring for the Roar inside five minutes, only for Matt Jurman to equalise almost immediately.
Janko then struck in the 38th, 52nd and 75th minutes, his first and third strikes coming from the penalty spot, but a spot-kick from Andrija Kaluderovic made it 4-2 and Brisbane got within one through Steven Lustica.
A fifth Sydney goal, from Alex Brosque, seemed to have wrapped things up, but Brisbane were not finished and pulled another goal back through former Sydney man Dimitri Petratos before time ran out.
Sydney now sit a point behind leaders Wellington Phoenix, while Brisbane remain seventh, two points outside the top six.
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