Penrith are preparing for a worst-case scenario of all four of their Holden State of Origin stars being unable to back up for Friday night's clash against Canberra at GIO Stadium.

Combined with the usual rigours of Origin football, the two-day turnaround has resulted in the Panthers dealing with the possibility that Nathan Cleary, James Maloney, Reagan Campbell-Gillard and Tyrone Peachey could also miss the Raiders match.

Isaah Yeo has played three of his 12 games this year in the centres to cover for injuries, but will be named in the back-row on Tuesday.

However, out at the Panthers Academy on Monday, he trained in the centres.

"I've been playing a bit of back-row and in the middle the last few weeks," Yeo told NRL.com.

"It all depends how the Origin boys pull up...but if they all get through unscathed, I'll stay where I've been the last couple of weeks.

"If anything happens to Tyrone Peachey, touch wood nothing, then I presume I'd go back into the centres. If he's fine and can play, I'll stay where I am."

Campbell-Gillard averages 65 minutes per game for the Panthers but is unlikely to spend the same amount of time out on the MCG on Wednesday night.

Penrith front rower Reagan Campbell-Gillard. ©Gregg Porteous/NRL Photos

If the towering prop misses the Raiders match, Nick Lui-Toso worked with the forwards on Monday and would make his NRL debut.

Penrith is lean in the prop department, losing Sam McKendry (knee) and Tim Browne (bowel) for the season.

Cleary and Maloney seem almost irreplaceable but local juniors, Tyrone May and Jarome Luai, played in the Panthers 2015 under-20s NYC grand final team and trained in the halves on Monday.

"Jarome has been playing awesome footy in NSW Cup and Tyrone played a handful of first grade last year [nine games] and he could do the same again," said second-rower and Fiji international Viliame Kikau.

"He knows the pressure and he knows what to expect in a NRL game. So if our No.6 and No.7 don't come back, I know we'll be okay."

Yeo said there was no feeling of dread that the Panthers top-of-the-table position might be threatened during the Origin window.

"Obviously we are training as if the boys aren't playing, but if they do, then that's a bonus," he said.

"We are winning at the moment so we need to continue that. If they are playing for us we're a better side but they've got to worry about playing for their state (NSW) first.

"And frankly it's been like that all year. We've been struggling with injuries but we've shown our depth and that we can live up to people's expectations."

Penrith do welcome back one key player from the casualty ward – skipper and hooker Peter Wallace (shoulder) – although he didn't train on Monday due to a virus.

Sione Kata has been playing No.9 and will most likely be named No.14 for the Raiders with Wallace back from three weeks out.

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"Having that old head in the team is so necessary," Kikau said of 32-year-old Wallace's return. "We've got a young team with everyone around early to mid-20s.

"I'm only 23 so we need that experienced head in big games and under pressure.

"That what Pete [Wallace] does. He's our leader. James [Tamou] and Trent [Merrin] help that way too – more old heads talking to the boys."

Yeo has a firm off-field friendship with Wallace and is also looking forward to seeing his ginger locks directing traffic again.

"He's so motivating when he's playing. He gives everyone around him a boost," Yeo said.

"He's phenomenal for us; a phenomenal leader. I've got the utmost respect for him."