St George Illawarra centre Mark Gasnier remains in extreme doubt for Saturday night's NRL preliminary final against Melbourne after failing to take part in Thursday night's training session in Wollongong.

Gasnier, recovering from an abdominal injury which forced him to miss last week's semi-final win over Manly, ran at about 70 per cent earlier in the day when put through his paces during an individual session with the team's medical staff.

The Test centre had been hoping to be running at full pace by Thursday, but was forced to sit out Thursday night's team session, coach Nathan Brown rating his chances of playing only "50-50".

"From our point of view as a group we're preparing as if Mark Gasnier won't be playing and if he passes a fitness test and he plays it will be an added bonus, Brown said.

"The doc said give him the fulltime, he's 50-50.

"He feels good but in September players always feel good, they want to be playing.

"Until he actually stretches out 100 per cent and the doctor's there to see how he's feeling, we won't know."

That may not be until Saturday, which would mean Gasnier would not have trained with the rest of his teammates in almost two weeks heading into the clash with the Storm.

The Dragons will hold their final session behind closed doors on Friday, rookie Darryl Millard to continue training in Gasnier's place.

Meanwhile Brown on Thursday said he was unconcerned by the club's poor disciplinary record under referee Steve Clark, claiming that the veteran whistleblower would be "pleasantly surprised" by the Dragons new attitude come Saturday night.

Clark was this week appointed to the grand final qualifier between Melbourne and St George Illawarra at Telstra Stadium, his first match involving the Dragons since Brown was fined $15,000 by the NRL for claiming Clark unfairly targeted his side.

A more disciplined Dragons outfit has lost only one penalty count since Brown's outburst - leading many to claim the $15,000 was money well spent - but the Dragons coach says it is all about a new attitude.

"Clarkey wouldn't have reffed a Dragons side that's had the discipline that he's going to ref this week," Brown said.

"Obviously referees talk like players talk and the feedback from all the referees has been they can't believe the turnaround in our attitude.

"I think we've averaged four penalties a week for the past six or seven weeks and I don't see how that's going to change this week.

"We've had some players who have been offside with some referees in the past who have made a good conscious decision to do the right thing.

"Not only have they turned the club's fortunes around but they've turned their own form around in a lot of ways.

"It's a positive thing - to know you can go out the and you know you're not going to have a drama with the referees is great.

The Dragons opponents Melbourne arrive in Sydney on Friday afternoon.

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