Ponga, the Newcastle skipper and Queensland Origin fullback, has been sidelined for the past two games after suffering his fifth head knock of the season in the Knights' round-19 loss to Sydney Roosters.

He has been ruled out of Saturday's clash with Brisbane and, after undergoing a series of neurological tests, it remains unclear if he will return for the Knights this season.

The 24-year-old has resumed training with his teammates - albeit wearing a bright-yellow vest that signifies "no contact" - and has reportedly indicated he is suffering no lingering effects.

Knights officials are waiting for confirmation from his specialists as to when their highest-paid player can resume, but CEO Phil Gardner told the Newcastle Herald recently the club would add an extra "layer of caution" to whatever the experts advise.

If Ponga is unable to play in any of Newcastle's four remaining games, there might still be a chance for him to prove his fitness to Kangaroos coach Mal Meninga.

The Herald understands that discussions are in progress to resurrect the annual Prime Minister's XIII game, which hasn't been played since 2019 because of COVID.

If that game is confirmed, it will likely to be scheduled for the third weekend of the NRL play-offs.

That potentially allows Ponga two months' respite after his most recent concussion, which occurred on July 22.

It would seem unlikely that the Australian selectors would consider taking Ponga to the World Cup, which starts on October 15, unless they have seen him play a game beforehand.

Man of the match in Origin III, Ponga said last month: "I'm not thinking too far ahead, but ... obviously I would love to go away and be a part of that [Kangaroos] squad and have that experience."