Penrith coach Ivan Cleary concedes Liam Martin's recurrent hamstring injury is becoming a cause for concern after the back-rower failed to finish his first game in more than a month.
Martin was a last-minute scratching for March's round-four clash with Parramatta after tweaking his hamstring, with Penrith hopeful he would return the following week.
His comeback continued to be a game-by-game proposition for another three weeks until Martin made his comeback in Saturday night's 16-15 defeat of Newcastle at McDonald Jones Stadium.
But he played only 34 minutes before being replaced and Cleary confirmed after the match it was the same troublesome hamstring that had forced the substitution.
"He's not that great, he felt it early but kept playing," Cleary said.
"It's a bit of a mystery, it is a concern. Hopefully we can get to the bottom of it."
As had been the case in previous weeks, Martin's injury had not initially felt serious before taking a turn for the worse.
"(It was) the same kind of story that we've had recently where it doesn't seem that bad," Cleary said.
"I'm not a medic but it's frustrating for him and frustrating for us."
Martin has played only two-and-a-half games this season and missing more time could affect his chances of retaining a spot in NSW's State of Origin side.
The 26-year-old is among a handful of players to have capitalised on the Panthers' strong club form to become a stalwart of the Blues' set-up in recent seasons.
Panthers five-eighth Jarome Luai said Martin's mental wellbeing was of primary concern given the frustrating nature of his injury.
"I'm not really worried about Origin, I'm just worried about his wellbeing," Luai told AAP.
"It's hard. Most of this game is mental.
"It might be affecting him now off the field. Those hamstrings are hard to contain. It might feel good one session and then feel bad the next.
"As a mate, I want to look after him."
Martin played on Luai's left edge for his cameo on Saturday night and the five-eighth is backing his teammate to make an imminent return to the fray.
"I've been back very early with a lot of my injuries, maybe it's working for me and I can pass on some tips," Luai joked.
"We know Marto. We know he's resilient and he'll be back out there in no time."
