Young Penrith star Dallin Watene-Zelezniak could face a lengthy stint on the sideline as doctors on Wednesday tried to work out how he had suffered a collapsed lung.

The 20-year-old, who has excelled for the Panthers at fullback since Matt Moylan injured his ankle in the round 12 match against Parramatta, was taken to hospital on Tuesday night suffering what was described as "terrible" pain.

Out of action: Dallin Watene-Zelezniak. Credit:Getty Images

Medical staff were said to be deciding whether the problem needed to be operated on, but when contacted by Fairfax Media, his manager, Tyran Smith, said there had been a suggestion it was most likely it was the result of a big hit in Penrith's last-start loss to the Sydney Roosters.

"I'm just waiting on more information," Smith said. "Dallin was in a lot of pain and our main priority is to ensure he is OK."

The Panthers also face the prospect of being without tough prop Nigel Plum for this Friday night's heritage round against the Melbourne Storm.