Cronulla are bracing for the prospect of being without inspirational captain Paul Gallen for Friday night’s blockbuster NRL preliminary final showdown with the Melbourne Storm.

Gallen suffered a shoulder injury in the second half of the Sharks’ heart-stopping 21-20 semi-final win over Penrith and is racing the clock to be fit for the grudge match with their 2016 grand final rivals at AAMI Park.

Cronulla coach Shane Flanagan said there is no fracture in the shoulder, however there is some ligament damage.

“There is no fracture but we won’t know too much until we see how it responds to treatment and how it settles down early in the week,” he said on Sunday.

At 37, Gallen delivered one of his best performances of the season before the Sharks needed a Chad Townsend field goal five minutes from fulltime to win after having led the Panthers 18-0 at Allianz Stadium.

The Sharks are also sweating on fellow forward enforcer Luke Lewis to recover from a calf injury.

He is hopeful of taking his place against the Storm, with the retiring veteran insisting he’ll be “sweet.”

“I’ll be fine mate, to be honest with you,” Lewis told AAP after the game.

“I’ve just got to get through the next couple of days, get all the swelling down.

“But it’s just a cork in a crappy position. It is what it is, though. I’m not too stressed about it.”