The versatile Australian back suffered a recurrence of a leg injury in last Sunday's victory over Widnes and has been ruled out of the elimination play-off against Bradford at Odsal.
"There's a chance he will play again this season if we go further and there's a chance that he won't," said the London coach, Tony Rea.
"It's a blow, but we're pretty comfortable with what we've got. Zeb Luisi has been outstanding for us during Mark's absence."
Rea rates the Bulls as the hardest draw in the play-offs, now that they have put their early season stutters behind them and got into a rich vein of form.
"They have really got some momentum and we will have to work very hard to overcome that," he said. "They have been finishing matches very strongly, which makes them difficult to play against, but no game is the same as any other."
The Broncos' next defeat will be their last under that banner, as they are destined to become Harlequins RL next season, and Rea has used a sense of history as an extra motivation for this evening.
He has told his players that making further progress in the play-offs will make them the best side in the Broncos' history. "It's something we've talked about, but, as well as that, I want them to be selfish and go out and win it for themselves."
The main motivation for the Bulls' captain, Jamie Peacock, is to finish his Bradford career in a way that shows his continuing commitment to the cause.
Peacock is to join Leeds next season and has been the subject of vitriol from some Bradford fans since that announcement was made.
"There's probably still one of two of them who can't accept it, but I have to thank our chairman, Chris Caisley, for what he has said about it. That has helped a lot," said Peacock
Caisley urged the supporters to get behind a player who has always given his all for the club, and most have done so.
"Whilst it's nice to be a fans' favourite, it's your peers knowing that you are genuine that is the main thing," Peacock explained.
Michael Withers is still missing, but Jamie Langley is in the Bulls' squad after signing a new, two-year contract on the eve of the match.
Langley had looked set to join the exodus from the club, but insists that he is happy to stay.
The Castleford utility back, Jon Hepworth, is to join the Irish rugby union side, Leinster, but will play for the Tigers in the National League grand final, should they get that far.Reuse content