NSW Blues halfback Nathan Cleary will miss the remainder of the 2023 State of Origin series after enduring a hamstring injury on Sunday night.

The Panthers confirmed on Monday morning that Cleary would be sidelined for six weeks, ruling him out of Game 2 and Game 3 of Origin.

Around the 15th-minute mark, the halfback was seen clutching at his hamstring after running back into the defensive line. He would go on to leave the field and not return for the remainder of the game.

"Scans have revealed the representative halfback will be sidelined for up to six weeks," a club statement from the Panthers read.

Nathan's father, Ivan Cleary, spoke to the media last night following the incident.

"It's going to cause a bit of mental disarray for a while," he said.

"Nathan is not just a halfback, he's one of the best in the game and he does a lot for our team ... a lot of things revolve around him."

"We're going to be without him for a while, so we'll learn a lot from that game tonight and push ahead."

It is a massive blow for the Panthers but an even bigger one for the NSW Blues.

Trailing the Origin series 1-0, the omission of Cleary will lead to a different outlook of the side. So far, the front-runners for the halfback position include Adam Reynolds, Mitchell Moses and Nicho Hynes.