Prop Tevita Pangai Jnr (hamstring) missed the 48-6 loss to Melbourne last week, did not train on Tuesday and is rehabbing his injury.
Hooker Max Plath (calf) and middle forward Ray Stone (neck) are both racing the clock. Captain Jesse Bromwich and five-eighth Kodi Nikorima will both miss Saturday night's clash with concussion.
The Dolphins and Broncos, both on 26 points, are two points behind eighth-placed St George Illawarra and seeking two wins in the final rounds to play finals.
Dolphins prop Mark Nicholls conceded it was still unknown what team would take the field, with the captain's run on Friday to prove decisive.
"We had a meeting this morning and we said we don't really know who is going to be playing and who is not," Nicholls said.
"We were already going to be without Kodi and Jesse. We realise how big this game is for us. It is do or die, same for the Broncos, and our season is on the line.
"We are just going to have to wait until Friday to see which team is going to run out which is not ideal but it makes the story better if we win."
The Dolphins have not beaten Brisbane in their history.
Corey Oates celebrates after scoring a try in Brisbane's win over the Dolphins in round six. (Dave Hunt/AAP PHOTOS)
"You play every game wanting to win. The Broncos are a big club and this is only our second year in the competition," Nicholls said.
"At the moment they are up 3-0 and personally I would just love to get a win against them. In that 'Battle of Brisbane' we are going to have 50,000 fans and hopefully they are all Dolphins fans and we can get a win for them.
"We now know we have to win two games to play finals. If we do manage to win those two games it is a good warm-up (for finals) for us."
The Dolphins have lost five of their past six games to slide out of the top eight after appearing assured of a finals berth two months ago.
Second-half fadeouts continue to be an issue.
"We have had injuries. That happens at every club but we have just been a bit inconsistent with our performances," Nicholls said.
"We have played really well in patches and matched it against some of the best teams and we have had some close losses which have hurt us."
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