Penrith have saluted the replacement parts in their NRL juggernaut as Blaize Talagi and Isaiah Papali'i came to fore to lift the Panthers out of a slump and rekindle the club's premiership defence.

The club's major off-season additions, former Parramatta five-eighth Talagi and ex-Wests Tigers forward Papali'i, have taken time to click into gear through Penrith's unconvincing start to 2025.

Talagi had to wait until last week's loss to the Dolphins for a shot in the halves while Papali'i chopped and changed between the bench and starting at prop.

But in Saturday's 40-12 win over the Sydney Roosters, which gave Penrith a 2-5 start after a run of five-straight losses, Papali'i found his groove off the interchange.

The forward maintained the rage when front-row wrecking balls Moses Leota and Liam Henry came off for a breather and New Zealand international Papali'i finished with a maiden Panthers try and 116m.

"He was really good 'Ice', he's been good for us each week but the way the games have gone, he's just probably been chewing up a lot of energy," said coach Ivan Cleary, who shunned the comforts of the coaches box to watch Saturday's drought-breaking win on the sidelines.

"We probably didn't get the best of what he's really good at, so we made the switch tonight.

"Moses was outstanding in his second stint and all our leaders were really good.

"That's what we need, it was good for some of the young boys too to get some confidence."

Talagi will be one of the inexperienced Panthers to be savouring a rare win.

The ex-Eels prodigy has played 22 NRL games to date, but this was just his fifth victory in the top grade.

Talagi has big shoes to fill in replacing Jarome Luai as Nathan Cleary's sidekick in the No. 6 jersey, but the halfback was jumping for joy when his junior partner scored his first Panthers try.

"I was pumped for him, he seems like a little brother at the moment," Nathan Cleary said.

"You just forget he's only 20 years old, he's so raw but he is so willing to learn.

"I've really enjoyed it so far, we are constantly building.

"We're starting to build those reps on the field and while it's definitely a work in progress it's something I'm looking forward to and I'm excited about.

"His second half tonight, in particular, he did some, did some great things."

Penrith's win in which they displayed all the patient, grinding football that has led them to four-straight titles was not without controversy.

An interchange bungle led to the Panthers briefly having 14 men on the field on Saturday when Izack Tago came onto the Allianz Stadium pitch while Scott Sorensen was receiving treatment in backplay.

Neither player impacted the match and Penrith, who were docked two interchange cards, are likely to only face a fine.