In Newcastle's past two games, against Manly and Parramatta, Ponga has been clipped by opposition players in mid-air and crashed to earth dangerously after launching himself to catch high kicks.

Given the Queensland Origin representative's ability to soar like a high jumper, any contact while he is airborne puts him in a highly vulnerable position.

O'Brien said he had no problem if rival players were genuinely competing for the ball, but added that NRL law enforcers had promised in the pre-season to crack down on deliberate spoiling tactics.

"You can't touch a winger in the air these days, but it seems like they forgot about the fullback," he said. "We spoke about not hitting wingers in the air, but there's a lot of contests on fullbacks at the moment. They're getting knocked around."

O'Brien said he would share his concerns with referees boss Bernard Sutton and NRL head of football Graeme Annesley, but would also remind Ponga's teammates that defusing bombs required a team effort.

"We need to get numbers back there to help him, and we need to put pressure on the kickers so they can't put it on the spot," he said.

"I think everyone needs to play a part in it."

Ponga found himself on the receiving end of three dubious incidents involving Waqa Blake during Sunday's 10-4 loss to Parramatta and was taken from the field for a head-injury assessment (HIA), for the second consecutive week. Blake was placed on report for a late hit in the 34^th minute but escaped any sanction.

"I thought it was late," O'Brien said of the tackle.

"It was probably a direct hit to the chest, but there should have been something [done] around the late contact."

Ponga has undergone three HIAs in the past six games, but each time he has been cleared to continue.

"He's 100 per cent," O'Brien said. "He's already passed the protocols, although we might look after him this week with modified contact."

O'Brien said Ponga's confidence was intact. "Knowing the kid that he is, he just accepts his role and understands that it can happen ... he's a tough kid. There's no doubt about it," he said.

Meanwhile, Knights prop Daniel Saifiti was scheduled to have scans on Monday afternoon to determine the severity of a knee injury he suffered against Parramatta.

The early diagnosis was that the NSW Origin representative had torn his posterior cruciate ligament and the club was hoping there was no damage to the meniscus as well.

In the best-case scenario, he appears likely to be sidelined for about a month.

Newcastle are expected to welcome back Sione Mata'utia (concussion), Mitch Barnett (neck) and Connor Watson (ankle), but Queensland Origin middle forward Tim Glasby is set to miss his third successive game after suffering a series of head knocks.

"He's still a little bit symptomatic, so we're getting him thoroughly checked out before we decide where to proceed from there," Knights coach Adam O'Brien said of Glasby.

Glasby has been liasing with Professor Chris Levi, who runs the Sports Concussion Clinic at John Hunter Hospital. O'Brien said the health and welfare of his players always came first.

"At the end of the day, Tim's No.1 job on this planet is being a husband and father to his kids," O'Brien said. "Football comes after all that."

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