A shoulder injury to James Fisher-Harris has soured Penrith's hoodoo-snapping 26-18 defeat of bogey side Parramatta.
Friday night's win in Penrith marked the first time since 2021 the otherwise all-conquering Panthers had defeated their local rivals in an NRL regular-season game.
The Panthers were still not back to their triple-premiership winning best, bombing certain tries either side of the break and proving uncharacteristically leaky on their goal line in the first half.
But back-to-back tries midway through the second stanza turned a two-point half-time deficit into an eight-point lead and had the Panthers on their way to a maiden win of 2024.
"Lots of things we came to do tonight, we did, but (there were) some very uncharacteristic defensive lapses," said Panthers coach Ivan Cleary.
"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."
Talismanic prop Fisher-Harris did not come back after leaving 15 minutes before the half and was unable to return to the sidelines to watch the remainder of the game, either.
He is set for scans this weekend.
"We'll know more after that," Cleary said.
"He did it early in the game, he was just losing power."
Lindsay Smith appears the likeliest candidate to start in the front row if Fisher-Harris needs to miss next week's grand final rematch against Brisbane.
Panthers' five-eighth Jarome Luai also faces an anxious wait after first going on report for a high shot that concussed Bailey Simonsson, and then again for tripping Mitch Moses.
The Eels had to reconfigure their left edge after losing Simonsson in the opening minutes, with bench back-rower Kelma Tuilagi forced to play out of position at centre.
"It hurts," Eels coach Brad Arthur said of losing Simonsson so early.
"But I thought those guys that we put there had to adjust and they scrambled well. They did the best they could in the position.
"I thought we were extremely tough."
The reshuffle gave Penrith an outlet to attack from long range. Their first two tries came after Izack Tago breaks down the right, with Tago's outside man Sunia Turuva grabbing their third.
But twice in the first half, the Panthers misfired the final pass before they could turn other line breaks into tries.
Brian To'o and Liam Henry each spilt the ball at close range to bomb two certain tries either side of the break.
Dylan Brown was the Eels' most effective player with the footy.
The five-eighth reignited his combination with Shaun Lane that found so much success in 2022 with a short ball that put the rangy back-rower over for the Eels' second try.
The Eels had an unlikely 18-16 halftime lead when Brown sent a flat pass to J'maine Hopgood at close range.
But after the break, as Tuilagi went down injured in backplay, Isaah Yeo fired a pinpoint perfect kick to Turuva for the winger's second try of the night.
In Penrith's next set, Tago - immense with 255 metres - skipped through the defence as the Panthers finally appeared at their clinical best with the ball.
In the second half, Tuilagi appeared to injure a shoulder attempting a big shot on Liam Martin, forcing Bryce Cartwright to become the Eels' third left centre for the night.
With Maika Sivo still suspended, the Eels will likely need to call on Haze Dunster to play wing against Manly next weekend as concussion protocols rule Simonsson out.
