Newcastle Knights forwards Tyson Frizell and Jacob Saifiti are entitled to be confused, and disappointed, after being dropped from the NSW squad for Origin II in Perth on Sunday.

Frizell and Saifiti were included in the 22-man squad for the series opener on June 8 but, other than spending more than a week in camp with the Blues, played no game-day role in the 16-10 loss to Queensland at Accor Stadium.

The defeat, and the unavailability of centre Jack Wighton because of COVID, prompted NSW coach Brad Fittler to make a host of changes to his roster for the must-win second game.

Saifiti, who was the only spare prop in the squad for Origin I, has been leapfrogged by two more experienced front-rowers in Manly's Jake Trbojevic and North Queensland's Jordan McLean.

Trbojevic, a surprise omission from Origin I, has been rushed into the starting line-up to partner Payne Haas in the engine room.

McLean has been named in jersey No.20, replacing the still-uncapped Saifiti in the list of standby players.

Frizell, a 14-game NSW veteran, has been bypassed after Fittler sacked St George Illawarra back-rower Tariq Sims and recalled Angus Crichton (Sydney Roosters) to his interchange rotation, as well as choosing Cronulla utility Siosifa Talakai for his debut and naming Roosters enforcer Victor Radley on his extended bench.

The head knock that forced Frizell from the field during Sunday's 20-18 loss to Canberra might not have helped his cause. If he had been chosen, he would have needed to pass concussion protocols before he was cleared to train in full with his teammates.

As expected Queensland retained Newcastle duo Kalyn Ponga and Dane Gagai, who were both outstanding for the Maroons in game one.

Knights coach Adam O'Brien was confident the stomach virus that laid Ponga low in Canberra on Sunday would not be an issue.

"He'll be on top of it now," O'Brien said after Sunday's game. "This is probably at its peak.

"The doctors are with him there. They've just got to get his fluids back up and get some food into him."

O'Brien said Ponga had not eaten "for a few days" leading into the clash with Canberra.

"He doesn't get a lot of raps for his toughness, Kalyn," O'Brien said. "There are people who want to get stuck into him a bit. I know and we know, the club and the players know what we've got with him. I wouldn't swap him for anyone."

Meanwhile, the Knights will have two players on either team in the under-19 Origin match at Leichhardt Oval on Thursday.

Oryn Keeley and Max Bradbury (NSW) will go head to head with clubmates Paul Bryan and Eddie Hampson (Queensland).

In the women's under-19 Origin, the Knights have provided Jules Kirkpatrick and Mia Middleton for NSW and Emma Paki for Queensland.

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