Knights legend Matthew Johns queries Kalyn Ponga's future at five-eighth

Ponga's immediate future remains in doubt after he suffered an ugly concussion in Sunday's win over Wests Tigers, when the five-eighth received a blow to head making a tackle.

It's Ponga's fourth concussion in 10 months, and came in his second NRL game back from sitting out the end of last season following repeated head knocks.

Johns on Monday would not enter into speculation on Ponga's future in the game, concerned about what impact it may have on the 24-year-old's mental wellbeing.

But he can see a potential need for the Knights to put him back in the No.1 jersey when he does return from the latest knock.

Ponga has been required to make an average of three tackles a game while playing fullback throughout his career, compared to 12 at five-eighth.

Johns said he had spoken with his brother Andrew about the issue on Sunday, with the rugby league Immortal a halves coach at Newcastle.

"When you are a kid and your whole life you have defended in the front line, there is so much of defence that is intuition," Matthew Johns said on SEN.

"You just know where to place your head, where to place your feet. How to drop, when to drive.

"It doesn't safeguard you from concussions ... but for (Ponga) this is a whole new kettle of fish.

"Yesterday the guy was going towards him with a bit of footwork and he got his head caught in an awkward position. That can happen to anyone.

"But if Kalyn is their most important player, which he is, then they have to make a decision on where he best sits in the side."

Ponga's positional question mark is made trickier by the fact Lachlan Miller has impressed at fullback for Newcastle, and they lack depth in the halves.

"These are a lot of really big decisions that sit in the lap of (coach) Adam O'Brien," Johns said.

"The art of that defence, at the last second to get your footwork right and get your head on the right side, it is something that is learned over a long, long time."

Johns' comments came as Luke Keary threw his support behind Ponga, advising the fullback to block out talk about the head knocks.

Keary has suffered several concussions through his career, with the Roosters often taking a cautious approach.

"Everyone will want to have their opinion on it, and probably best for him to turn the TV off, put the phone down and go talk to the right people," Keary said.

"Don't listen to everyone else.

"It happens in footy and when you get a few in a row it gets highlighted a bit more. I know the doctors will do the right thing for him, whatever that is."

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