Guerra lasted only a few minutes of Newcastle's 36-20 loss to Blacktown Sea Eagles and was frustrated about missing out on the chance to gain some match fitness, after a lengthy lay-off recovering from a fractured ankle.

But the media coverage last week relating to a possible class action by former players against the NRL was a reminder of how serious the issue of concussion is.

"Personally, for me, I'm not too worried, because I haven't had any real issues with it [concussion] in my career," Guerra said.

"There are players that do, and I guess it's up to them how they deal with it.

"For me, I think the protocols these days are for the safety of the players. Although I wasn't too happy when I wasn't allowed back on the field, it was probably the right call for me, when I played in Canterbury Cup.

"Everyone knows across the board, even as players, as much as we want to be out there, there is a point where our safety has to be taken out of our hands and it has to be given to somebody else.

"I feel like the docs are doing a pretty good job there."

Guerra described his incident against Blacktown as "a minor knock", hence his initial disappointment about being replaced.

"I didn't lose consciousness, I didn't lose memory," he said.

"It was just a bit of a glancing blow, and it took me a while to find my feet and get my bearings."

He said that over the course of his 185-game NRL career, he had endured relatively few such episodes "when you compare it to how long I've been playing".

"Concussions, they're going to happen, because we are getting bigger, faster and stronger ... there is definitely an area of concern, and I think the game is addressing it really well," he said.

Guerra played 27 minutes off the bench in Saturday's 24-20 loss to the Warriors, which was his first top-grade game since fracturing his ankle against Manly on April 13.

The 31-year-old will be hoping to retain his spot for Friday's clash with Canterbury at McDonald Jones Stadium, although Knights coach Nathan Brown might have four Origin representatives - David Klemmer, Mitchell Pearce, Daniel Saifiti and Tim Glasby - available to bolster his squad.

"I think there'll be a few battered and bruised people [after Origin III], but we're all just going to hope they come back fit and healthy," Guerra said. "And if the coach puts them in, then I'm sure they'll play well. If the coach decides to rest them, I'm sure who fills their spot will play well, as well."

Guerra said the Knights would not be underestimating last-placed Canterbury.

"We probably treat every week like a must-win," he said.

"It's a bit like that, this competition. You can't go up against any side thinking it's a sure thing.

"You've got to go in with the right mentality, otherwise you get found out.

"Our mentality every week is that this is a must-win for us ...two points is what you're after, and anything else is probably not good enough."