The Sharks on Saturday afternoon slumped to their heaviest loss under second-year coach John Morris, conceding a whopping 10 tries to the Panthers.

And there are fears Fifita, having failed to play after halftime, might join fullback Matt Moylan on the sideline for an extended period.

"He felt his hamstring so, yeah, we were trying to monitor him at the back end of the first half," Morris said, post-game.

"But when they done some tests on him at halftime, he couldn't go on with it. So he'll need scans. He couldn't finish the game, so that's a concern for us.

"Any hamstring is a concern. If you can't finish the game, you're thinking they're struggling for the next week. One or two weeks normally is a good outcome.

"But that's not confirmed yet. Hopefully, it's precautionary."

However, Morris has bigger problems than the health of Fifita, with his team's defence having no answers against Penrith's relentless attack.

Their left edge in particular was opened up by the Panthers' right, where debutant Charlie Staines bagged four tries.

Morris was forced to hand Nene Macdonald his club debut after Ronaldo Mulitalo fell short of coming back from a knee injury.

"There's some tries there that are just not good enough at this level," he said.

"Some blokes need to have a good hard look at themselves as far as how they were pulled apart there."

Morris was also upset with the five set restarts given to the Panthers, while he also said his team struggled to adapt to a series of concussion tests.

Bryson Goodwin, Siosifa Talakai and Sione Katoa were all forced from the field for examination, with only Goodwin cleared to return.

"So there's reasons around what hurt us today, but it's just not good enough. You're going to have that in the NRL every single week," Morris said.

"And it's about being able to perform under that adversity."

Australian Associated Press