Injury-ravaged Brisbane have taken another big hit with senior prop Nick Kenny ruled out of Friday night's NRL clash with St George Illawarra with a back injury.

The 27 year-old joins Justin Hodges, Israel Folau, Corey Parker, Jharal Yow Yeh, Steve Michaels and Denan Kemp in Brisbane's rehab club while two other front-line players, Ben Te'o and Antonio Winterstein will miss the battle after being dropped for disciplinary reasons for turning up late to weights training on Tuesday morning.

Kenny has a history of back problems having undergone surgery last year.

He trained on Monday but pulled up in considerable pain and a decision was made not to take any risks.

"Nick pulled up sore with a lower back complaint earlier in the week," said Henjak after his heavy underdogs trained impressively at Red Hill on Wednesday.

"Maybe we could have gone with him and hoped he came good by Friday but it just would have been another downer for us (if he couldn't play).

"We wanted to have a good training session today with everyone who's going to play."

Henjak, who has half his starting side out injured, could have done without losing Kenny from a side many pundits believe has no chance of toppling the Dragons or even getting close to them on the scoreboard.

They will field a backline which with the exception of halves Peter Wallace and Darren Lockyer, is almost unrecognisable.

Henjak was not displaying any outward signs of being concerned at Brisbane's predicament, preferring to set his players a challenge against the Dragons.

"When things get really tough, that's when you respond to adversity, that's when you start to become a really good team," he said.

The coach isn't worried about a potentially lopsided scoreboard or the end result.

"It's not about winning or losing or the scoreboard this weekend, it's how they compete and how they execute and how much they want to play for each other," said Henjak.

"Those are the things we're looking for.

"There's no pressure. It's not a semi final or a grand final, there's nothing on the line."

Brisbane muscled up on the Dragons in Wollongong in round 24 last year when their season was in jeopardy, with hooker Andrew McCullough producing his best game to inflict the major upset.

Halfback Wallace said the Broncos had won games in the past when down on troops.

"It's no secret it's a young team, it's younger this week than it was last week (against the Roosters)," Wallace said.

"That's no excuse. Everyone has a job do to and if we put in a good performance with everyone doing their best and competing for 80 minutes we'll be happy with that."

Some observers have dubbed Brisbane's trip to WIN Stadium with a side very short on first grade experience as "mission impossible" against the Dragons.

"I'm sure people think that with all the injuries and stuff but we can't look at it like that, we're picked to do a job and we all have to go down and perform to our best on Friday night," said Wallace.

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