Nathan Cleary’s hopes of playing for NSW in Game II of State of Origin hinge on the outcome of scans on Monday after he limped out of Penrith’s 26-18 win over St George Illawarra.

Cleary, who was part of the Blues side that lost the series opener in Adelaide, pulled up in pain after just 15 minutes at BlueBet Stadium.

Penrith is hopeful the halfback has suffered a “low-grade” strain but it leaves the prized No.7 in severe doubt to face the Maroons at Suncorp Stadium on June 21.

Cleary is critical to Brad Fittler’s plans as the Blues fight to save the series in Brisbane for the first time in Origin history.

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“It’s tough to speculate on the seriousness of it before he’s got scans,” NSW adviser Greg Alexander said in commentary for Fox Sports.

“But looking at those images, I guess everyone at Penrith is trying to be as positive as possible and hoping it’s low-grade. I’m hoping (for) the same thing.”

Fittler and Alexander would likely plump for Cronulla’s Nicho Hynes, who made his Origin debut from the bench on Wednesday, with Parramatta’s Mitch Moses and Brisbane’s Adam Reynolds possible understudies.

Cleary looked to have no signs of rust from the Origin opener, setting up winger Brian To’o with a floating cut-out pass in the 11th minute after a Zac Lomax penalty.

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Just after the halfback pulled up sore, Mikaele Ravalawa crashed in at the corner for the Dragons.

The Fijian winger added a second in the 38th minute with Lomax also nudging another penalty to keep the scoreboard ticking over for the Dragons.

Jack Cogger, who was brought on to replace Cleary, found To’o with a pinpoint cross-field kick on the stroke of halftime with the winger’s effort converted by Stephen Crichton.

After half-time, Crichton added a penalty and what followed was an end-to-end battle between the reigning premiers and the bottom-placed Dragons for the next 20 minutes.

There was a heart-in-mouth moment when Penrith’s NSW five-eighth Jarome Luai rolled his ankle but he was able to play on.

The rhythm eventually broke when touch judge Wyatt Raymond flagged for a knock on by Dragons winger Mat Feagai with Sunia Turuva touch down on the hour mark.

Lomax pegged Penrith back after lock Jack de Belin was knocked out cold from the restart but a Moses Leota try got the Panthers back in front with 10 minutes left.

Crichton converted Leota’s try to re-establish a six-point buffer and added a last-minute penalty to ensure the Panthers of victory.