Brisbane's premiership defence hangs by a thread after they were handed a sixth-straight NRL defeat in a 48-6 thrashing at the hands of South Sydney.
Five-eighth Cody Walker was the mastermind behind the Bunnies' victory on Thursday night as Wayne Bennett's side (7-6) strengthened their bid for a top-eight spot.
Walker had four try-assists and Alex Johnston grabbed a quartet of tries as Souths snapped a three-game winless run.
But the story of the night will be Brisbane's nosediving form as they returned to Accor Stadium for the first time since coach Michael Maguire engineered a drought-breaking premiership win nine months ago.
The Broncos began their losing run with defeats to top-four contenders in the Sydney Roosters, Manly and the Warriors.
But the last three weeks, where Maguire's men have been beaten by wooden spoon favourites St George Illawarra, struggling Gold Coast and an injury-depleted Rabbitohs side, have highlighted how far Brisbane have fallen.
The Broncos (5-9) are in danger of becoming the first reigning premiers to miss the finals in the following season since Wests Tigers finished outside the top eight in 2006.
And adding to Brisbane's woes, halfback Adam Reynolds (hamstring) and five-eighth Ezra Mam (shoulder) picked up injuries in the second half and failed to see out the match.
On an emotional night, where both clubs united to celebrate the life of Jai Arrow following his diagnosis with motor neurone disease, Souths raced out to a 12-0 lead when wingers Ed Kosi and Johnston scored in back-to-back sets.
Walker then sent a rampaging David Fifita over from close range before Johnston dived in for a second.
Souths constructed the try of the night when halfback Ashton Ward chipped over the Brisbane line for Walker, who tipped on for Jamie Humphreys to score and give the Bunnies a 30-0 halftime lead.
Josiah Karapani finally got the away side on the board in the 52nd minute, but there was no sense of fightback brewing.
Nothing summed up the Broncos' night more than Ben Hunt passing the ball into the back of Preston Riki when the forward was looking towards his own tryline shortly before Mam and Reynolds went off.
Johnston crossed two more times in the final 20 minutes, while debutant John Radel also touched down to help Souths run up a big score.