Billy Slater is out of the Storm's line-up for Friday night's clash against the Panthers due to a serious illness to a member of his family, but Ryan Hoffman is set for a shock return from a hamstring injury.
Melbourne coach Craig Bellamy says he's not guaranteed to be available for the first week of finals either, but will assess next week.
It's a huge blow to the Storm's efforts to win their third-straight minor premiership, considering the fullback ran for a career-high 302 metres against the Titans on Saturday and is in good form, and they'll need a solid victory to do so.
"Unfortunately there's been an illness in his family up in north Queensland," Storm coach Craig Bellamy said.
"Family's more important than footy. The family's going through a reasonably tough time at the moment."
Jahrome Hughes is the likely candidate to play fullback and return from injury.
The Storm have endured plenty of injuries and suspensions in 2018, but Bellamy is proud of the prospect of wrapping up another JJ Giltinan Shield.
"It's a strange feeling I suppose," he said.
"At the end of the day, I'm really proud of these players and what they've been through this year, and what they've got us to.
"To be in the spot we're in at the moment, it's great testimony to the amount of effort and training in games that they've put in. There were games where we've been clunky. A lot of our wins have been pretty ugly, but we've just found a way."
Bellamy admitted being surprised by Ryan Hoffman's possible return from injury well ahead of schedule.
Hoffman has amazed Storm medical staff to earn inclusion in their 21-man squad for Friday's clash with Penrith, with a final call on his fitness to be made after Thursday's captain's run.
"I didn't know there were three hamstring muscles," Bellamy joked.
"Apparently the muscle that he tore doesn't really affect him much functionally as far as running goes.
"He's been ticking the boxes all week, and just needs to tick one today (to be ruled fit to play)."
Bellamy wants to see his team build their attacking game in time for the finals next week.
"I think the last couple of weeks, our defensive effort has been outstanding, eight points and four points scored against us," he said.
"It's where we want to base our game and lay the foundations. With so many players going in and out at the moment, it is hard to get your attack flowing as smoothly as you like."
Bellamy also paid tribute to retiring greats Johnathan Thurston (this weekend) and Simon Mannering (during the finals series), praising their terrific careers and holding them in high esteem as ambassadors for rugby league.