Apisai Koroisau says the respective trials and tribulations of Ivan Cleary and assistant Trent Barrett during their four-year Panthers hiatus have done both "a world of good" as Penrith gun for a record ninth straight win.

Koroisau and Barrett have returned to Panthers HQ this season after exiting in 2015, the same year Cleary was infamously moved on by Phil Gould as well, to play key roles in the club's stunning resurgence.

A victory over the Warriors on Friday would be Penrith's ninth on the trot and the longest winning streak in club history, bettering the eight-game run en route to the 2003 premiership.

Penrith's last genuine tilt at the title came when Cleary and Barrett combined in 2014 to take the side within one game of an unlikely grand final appearance, with Koroisau arriving in the following off-season.

Cleary and Barrett then endured ugly splits with Wests Tigers and Manly respectively before finding their way back to Penrith, each spending at least a season in the coaching wilderness as well.

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Barrett will return to a head coaching role with Canterbury next season.

Having also been released early by the Sea Eagles to link once more with the Panthers, Koroisau has seen a stark maturing right throughout the club, starting with the two clipboard carriers.

"I think a lot has changed, a lot has fallen into place as well," Koroisau said of comparisons between Penrith then and now.

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"Trent Barrett has had a head coaching job and going through all of that would've helped him grow a lot.

"And obviously Ivan in that same amount of time, he was sacked and then came back. I think it's done both of them a world of good.

"I was at a different point in my life back then [in 2015] as well. Right now I'm a lot more mature and my focus is on winning and trying to get the best out of everyone.

"Whereas the last time I was here I came off a crazy year of football [a 2014 Rabbitohs premiership win] and I was pretty happy just getting paid and playing NRL.

"I was really immature outside of footy as well.

"But just the vibe around the place is a lot different. Everybody just seems to be on the same page.

"I think the coaching staff, Trent Barrett, Cameron Ciraldo and Ivan are working together as a team has been amazing with H [head of performance Hayden Knowles]."

It hasn't been all smooth sailing for Cleary - he was fined $20,000 by the NRL earlier this week for criticising the refereeing in last Saturday's win over Canberra and he indicated he would be submitting a response to head office over the sanctions.

Cleary's squad boasts less experience than all 15 of their rivals but continues to occupy pole position on the ladder.

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Not since their 1991 premiership-winning side have Penrith sat atop the ladder for three straight weeks, but Koroisau and company continue to defy the doubters with an undefeated run since their round-five loss to the Eels - their only defeat this year.

The livewire hooker says it is a rare position of dominance for the Panthers, but his younger teammates are quickly growing accustomed to the purple patch.  

"It's not until you are sitting at the top of the table you realise you are the hunted and not the hunters anymore," Koroisau said.

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"That's one of those things about Penrith. They're good at being underdogs. Out here in the west they have that blue-collar mindset.

"So to have that [different] kind of feeling coming into games is pretty cool.

"Knowing they are coming for us, a lot of the boys are happy to step up."