QUEENSLAND'S Kalyn Ponga has officially been ruled out of the State of Origin decider after sustaining a calf injury.

Newcastle on Sunday morning revealed that scans confirmed their star No.1 strained his calf and will miss up to two weeks.

Ponga picked up the injury during Game 2 of Origin in Perth a week ago and was a late withdrawal from the Knights' team for Round 15.

The Knights are hopeful of his return for Round 18.

"The nib Newcastle Knights can confirm Kalyn Ponga had scans on Sunday morning to determine the severity of his calf injury," the club said in a statement.

"The scans showed he has suffered a strain.

"Ponga picked up the injury during State of Origin week and sat out the Knights' 26-12 win over Brisbane as a result.

"He is expected to miss the next two weeks."

The star initially thought he would be fine to take part in the decider, before the injury flared up ahead of the clash against the Brisbane Broncos.

"I don't think I am in doubt for Origin, not at all. I think I will be sweet," Ponga said on Fox League this weekend.

"There wasn't a moment it just pulled up sore after the game.

"I had a cork that I was focusing on and because of the cork I wasn't using that leg much and the calf came through, so I should be sweet."

Cameron Munster, Anthony Milford and Michael Morgan are likely to come into consideration to be named Maroons fullback for the Origin decider on July 10.

- with AAP