The Panthers are hoping Cleary’s injury is not on the serious side, and he will only miss minimal matches. They play the Sea Eagles after the Roosters clash before having a bye in round six.

But the loss of the NRL’s best player, who mesmerised the Broncos in a five-star display last week, will be a big one for the three-time defending champions after back-to-back wins against the Eels and Brisbane.

The Roosters, meanwhile, will welcome back Luke Keary from the 11-day concussion stand down protocol. He will be paired with Sam Walker, who had a category one concussion assessment in the Roosters’ thumping win over South Sydney downgraded on appeal.

Jarome Luai is expected to take on primary playmaking duties with Cleary on the sidelines.

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It was a double blow for Penrith on Monday with back-rower Scott Sorensen out for a month with a knee injury.

The New Zealand international has only played two matches after being held out of the World Club Challenge and opening-round loss to Melbourne, with the back row an area of concern for the Panthers.

Nathan Cleary showed no immediate signs of the hamstring injury when he did a full suite of post-match interviews and a press conference following their convincing win against Brisbane.

The news will be of concern to NSW State of Origin coach Michael Maguire given Cleary’s hamstring woes in the past 12 months as he plots a Blues revival.

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