Penrith superstar Nathan Cleary is reportedly set to spend up to the next six months on the sidelines as the Clive Churchill medallist prepares for shoulder surgery.

It was revealed in the hours after Sunday's Grand Final victory that Cleary had suffered a shoulder complaint midway through the season, with the setback first sustained after Origin II.

It is understood that Cleary suffered a shoulder dislocation and labral tear, but was able to carry on through the remainder of the NRL season to lead the Panthers to premiership glory.

The 23-year-old is now set to require surgery on the injury and will go under the knife in the coming days.

The procedure is likely to rule Cleary out of any pre-season preparations, with the star halfback potentially spending up to six months on the sidelines and subsequently could miss Penrith's season opener for the 2022 season.

“When I first found out the prognosis of my shoulder, my physio called me straight away and said we will get you back," Cleary said told News Corp.

BRISBANE, AUSTRALIA - OCTOBER 03: Nathan Cleary of the Panthers runs the ball during the 2021 NRL Grand Final match between the Penrith Panthers and the South Sydney Rabbitohs at Suncorp Stadium on October 03, 2021, in Brisbane, Australia. (Photo by Chris Hyde/Getty Images)

“It’s a full credit to them and I can’t thank the physios enough for the work they put into me.

“They got me onto the field (for the grand final).”

Penrith great Greg Alexander revealed on Fox League after the Panthers' 14-12 win over South Sydney that Cleary was close to suffering major damage to his shoulder.

“The tendon was torn 80 per cent,” Alexander said.

2021 NRL Grand Final - Panthers v Rabbitohs
BRISBANE, AUSTRALIA - OCTOBER 03: Nathan Cleary of the Panthers celebrates with Matt Burton of the Panthers after he scored a try during the 2021 NRL Grand Final match between the Penrith Panthers and the South Sydney Rabbitohs at Suncorp Stadium on October 03, 2021, in Brisbane, Australia. (Photo by Bradley Kanaris/Getty Images)

“It was hanging and they tried cortisones to try and shock it into some scar tissue to strengthen it a little bit but I don’t think much of it worked.

“And he just strapped it up and got on with it.”

Panthers coach Ivan Cleary also revealed that fullback Dylan Edwards played through the Grand Final victory with a broken foot.