St George Illawarra sunk a massive $100,000 bet and continued Brisbane's finals misery with a powerful 20-4 upset in its NRL qualifying final at Suncorp Stadium.

The curtain hasn't fallen on the Broncos' premiership bid, but it is on its way down after they again failed to get their finals gorilla off their back.

Saturday night's loss was Brisbane's seventh straight finals defeat, and sixth in a row at the famous Brisbane ground, something not lost on coach Wayne Bennett.

"It's a hard place for us to win at semi-final time because teams all come here pumped up," said Bennett.

The Dragons played mistake-free football for the opening 40 minutes to lead 10-4.

A soft try the prop Luke Bailey, who strolled through Brisbane's defence in the 44th minute, and another 10 minutes later to centre Matt Cooper gave the Dragons a 20-4 lead that proved too much for Brisbane to come back from, despite the urgings of a huge crowd of 50,387.

Any hopes of a Brisbane comeback were dashed when fullback Justin Hodges, who battled on bravely after suffering a corked leg early in the clash, lost the ball over the line in the 62nd minute.

Most of the crowd thought Hodges had scored until replays on the big screen showed him losing the ball centimetres from the ground.

A supremely confident Kiwi punter dropped $100,000 with bookmaker Centrebet as Brisbane slumped to its seventh successive finals loss in a row since 2002.

Dragons coach Nathan Brown, conceding he could be without star centre Mark Gasnier (corked hip) next weekend, put his team's best performance of the season down to lessons learned from last year's finals failures.

"We're a much more relaxed football team this year," said Brown after the Dragons clinched their fourth win from their last five games against Brisbane in Brisbane.

"Last year we had the weight on our shoulders but I was really confident we'd play well tonight. I told the boss we'd win."

An exhausted Bailey said the game had been a cracker.

"That was semi-final footy at its best," he said.

"It was awesome, the goal line defence, that's what wins games."

Brisbane skipper Darren Lockyer said the Dragons could keep winning without Gasnier, who is facing one to two weeks on the sidelines, if they continued to defend with the same desperation as they did tonight.

"If you can defend like that and hold onto the football, any team in the eight will go a fair way," said Lockyer, who felt Brisbane had picked a bad night to play its worse football in a month.

Brisbane coach Wayne Bennett, confident Brisbane would live to fight another day, had no problems with his players effort in a clash played at a frantic pace, especially in the first 40 minutes.

"We were too impatient in the second half and our completion rate was down around 50 per cent."

After three weeks of dominating their opposition, Brisbane struggled to find a way back tonight but that was more to do with the Dragons defensive resolve than any lack of effort.

"We played the worst we've played in four weeks," said Lockyer.

"We haven't been 10-0 for a while but it will only make us hungrier."

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