Creagh could be missing for six weeks after he suffered three lower-back fractures in his side's 12-4 loss to Melbourne at Kogarah.

Dugan came from the field with 12 minutes remaining against the Storm, but was later cleared of a serious ankle injury.

However, Peter Mata'utia is expected to step in if Dugan fails a fitness test on Sunday.

Creagh told the post-match media conference that his back was "OK" but was surprised when scans revealed the extent of the injury he'd managed to play through against the Storm.

Dragons physio Dan Lawson said it was a brave effort to play through the pain.

"Its a pretty impressive effort," Lawson said.

"Ben sustained three transverse process fractures in his back which are basically small parts off the side of his spine in the lower-back area which is a significant injury.

"We suspected that that might have been the case to one of the levels of his lower back but to come back having fractures to three separate levels ... he was a bit surprised and we were a bit surprised as well. He will be out for at least four-to-six weeks.

"The amount of pain that he would have been experiencing on the field would have been significant and for him to stay out there and play the game the way that he did was a real testament to his character."

Creagh will be immobilised for at least a week and Lawson said medical staff will aim to have him running within three weeks before resuming contact sessions.

"The rehabilitation is fairly slow early on," Lawson said.

"In the first week he will not be able to do any exercise at all. Following that period we will start to get him back into some low-intensity exercise and after about two weeks we should hopefully get him back running and ultimately into weights and full contact."

Coach Paul McGregor is yet to name a replacement captain or lock for the clash against the Tigers at Campbelltown.

Origin rep Trent Merrin is the most likely starter having begun the match from the bench against Melbourne.

That would pave the way for Jake Marketo - named on extended bench on Tuesday - to end a two-year NRL exile.

Former Kiwi Test captain Benji Marshall is the frontrunner to assume the captaincy having skippered the Dragons at January's Auckland Nines in Creagh's absence.