Cronulla star Luke Lewis feared his NRL career was going to end sitting on an exercise bike at Allianz Stadium as he watched Penrith stage a dramatic second-half comeback after coming from the field on Friday night with a calf injury.

Lewis, who is retiring at the end of the season, hobbled to the sideline in the 62nd minute after helping the Sharks to a comfortable 20-8 lead with a first-half try but he could only look on as the Panthers seized momentum.

"I was sitting there in the last five minutes thinking 'wow, this could be it'." said Lewis, who spent the last 18 minutes pedalling an exercise bike behind the Cronulla bench.

"The week was just a different sort of preparation, knowing that you were preparing for a do-or-die clash and, if you lose, you're out and that's it, football's all over, so I am very happy that the boys got me over the line. It gives me another week at training."

Match Highlights: Sharks v Panthers - Finals Week 2, 2018

The 35-year-old, who started his career as a winger with Penrith in 2001, now hopes to have the opportunity to bow out with a third premiership after Chad Townsend kicked a 75th-minute field goal to keep Cronulla's season alive.

"It was definitely a relief when Chaddy hit that field goal over," Lewis said. "I am just stoked but we need to be better next week if we want to have a red hot crack at making the big one."

The Sharks play Melbourne at AAMI Park on Friday night for a place in the grand final, and Lewis and his teammates will go into the match with no fear about facing the Storm after winning both games between the two clubs this season.

For the former Test back-rower it will be an opportunity to end his 323-match NRL career on a high but he knows the Storm will want to send star fullback Billy Slater out with a premiership.

"The one thing I've always realised with Melbourne the whole time I've been playing rugby league is if you don't prepare, don't turn up ready to play for 80 minutes, they'll give you a hiding," he said.

"They've got great players all over the park. They've got one of the best coaches, I believe, in the world. He knows the game like the back of his hand and he knows how to prepare a side for big games so, for us, it's a massive challenge and we need to do everything to get ready.

"We need to tick all the boxes, we need to get down there feeling healthy and fit and we need to be ready to go for 80, not 40."

While Lewis is confident he will be fit to play, Cronulla captain Paul Gallen is bracing for a week of intensive rehabilitation in a bid to overcome the shoulder injury which forced him from the field against Penrith.

Scans have ruled out a rotator cuff tear and any fracture but Gallen has ligament damage in his left shoulder.

"The good thing about our club is that we have built up over the last six years that it is not just about one individual; whoever steps in needs to be able to take over the role," Lewis said.

"Hopefully by Monday when we are ready to run out on the field to start training we will know exactly what our team is and how we are going to prepare."

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