Penrith is sweating on the results of James Fisher-Harris's scans after the three-time premiership prop was injured in Friday night's 26-18 win over Parramatta.
But in positive news for the Panthers, five-eighth Jarome Luai avoided suspension, despite being placed on report twice.
Fisher-Harris could only manage to play 25 minutes in the Panthers' victory after leaving the field with a shoulder injury.
"He did it early in the game and he was losing power," Panthers coach Ivan Cleary said after the match.
"We'll know more after he has had scans."
Lindsay Smith appears the likeliest candidate to start in the front row if Fisher-Harris is ruled out of next week's grand final rematch against Brisbane.
Luai went on report for a high shot that concussed Bailey Simonsson, and then again for tripping Mitch Moses.
But he will be free to play the Broncos after being offered a $1,800 fine with an early guilty plea to each offence.
Friday night's victory was the Panthers' first over the Eels in a minor premiership match since 2021.
The Panthers defeated the Eels in the 2022 grand final but had struck out when the two teams had met during the past two regular seasons.
Panthers coach Ivan Cleary was satisfied to claim the first win of the season, but he said the three-time defending premiers had room for improvement.
"Lots of things we came to do tonight, we did, but there were some very uncharacteristic defensive lapses," he said.
"We left a lot of tries out there but the fact that we were creating chances the week after you don't score a point is pleasing.
"It was a good win."
The Panthers lost 8-0 to Melbourne Storm in the opening round of the season.
The Eels hold a 1-1 win-loss record following their defeat to the Panthers, having beaten Canterbury 26-8 last weekend.
ABC/AAP