Penrith's NRL top-four ambitions have been dealt a blow after fullback Dallin Watene-Zelezniak was ruled out for three weeks with a hamstring tear.
Watene-Zelezniak helped a depleted Panthers side end a worrying two-game slide with a 36-4 rout of the Warriors on Friday.
He ran a game-high 164 metres and broke five tackles but was substituted with seven minutes to go in the match.
Watene-Zelezniak had been a strong performer in the No.1 since taking over from Dylan Edwards after the first-choice fullback's season-ending shoulder injury.
Coach Anthony Griffin will now have to reach deeper into their depth, with centre Dean Whare a possible option to take the role for Friday's clash against Cronulla.
Reserve grade No.1 Caleb Aekins, who re-signed with the club for another two years last week, is another option to take on the Sharks, while youngster Jarome Luai has also played some fullback in the NSW Cup.
The match looms as a pivotal opportunity to cement a top-four spot for fourth-placed Penrith, however, Griffin could rest State of Origin trio James Maloney, Nathan Cleary and Tyrone Peachey.