Penrith Panthers star Nathan Cleary has a stress related foot injury, and is in doubt for the club's preliminary final.

While the Panthers refused to rule him out, the star halfback was seen limping at the back-end of the game against the Sydney Roosters on Sunday, and the club admitted afterwards they weren't sure what was wrong.

Cleary had scans on Monday, and it has returned an issue, although the Panthers have not flatly ruled him out at this stage with a fortnight to recover before what will likely be a Sunday afternoon preliminary final, to be played against either the New Zealand Warriors or Newcastle Knights, who clash in a sudden death semi-final at Eden Park this Saturday.

"Cleary sustained a stress-related bone issue in his foot during Sunday afternoon's Qualifying Final victory over the Sydney Roosters,' the Panthers wrote in a statement.

"Cleary will continue to be assessed and monitored by the Panthers medical team."

Cleary already had one stroke of luck on Monday morning, when the NRL's match review committee confirmed only a Grade 1 charge - and a fine to go with it - for an offence where he ran through Hugo Savala's leg as he kicked in general play.

Savala wasn't injured, and while Cleary was sin binned at the time, the MRC couldn't find the evidence to dish out a Grade 2 - or higher - charge that would have carried a suspension with it.

The star halfback will now focus on his recovery, with 14 days to turn it around before the grand final qualifier, however, if he has a stress frature of any description, playing again in two weeks would be a remarkable effort.

The Panthers aren't strangers to that though, with Isaah Yeo currently playing through a major pectoral muscle injury.