Darren Lockyer has backed Adam O'Brien to leave co-captain Kalyn Ponga at five-eighth, despite the former fullback suffering yet another concussion a fortnight ago.

Concerns were raised over the off-season over Ponga's head knock history after O'Brien announced their marquee man would be moving into the front-line, the latest player to follow Lockyer and switch from fullback to the halves.

It's been a popular move in recent years, with a large chunk of the NRL's halves contingent starting their career in the No.1 jersey.

Matt Moylan, Mitchell Moses, Cameron Munster, AJ Brimson, Jack Wighton, Jahrome Hughes, Adam Doueihi, Anthony Milford, Cody Walker, Te Maire Martin, Nicho Hynes and Ponga have all made the switch during their careers.

Former Knights coach Nathan Brown switched Ponga to the halves originally in 2019, the move lasting just three rounds before the club's 1-2 record saw him moved back.

Lockyer made the permanent switch in 2004, culminating in a grand final victory just two years later over the Melbourne Storm.

While the veteran knows how taxing the move can be, increasing your defensive workload by 400%, he's backing Ponga to continue his time donning the six jersey.

“When you are a fullback defensively, you might make the odd tackle from a scrum,'' Lockyer told News Corp.

“The next one is one-on-one or trying to tackle someone over the sideline. Rarely do you have a front rower or back rower running at you."

While Ponga suffered a category one concussion 80 seconds into their clash against the Wests Tigers, and is now in Canada for further testing, Lockyer's adamant it wasn't the switch that did the damage, it was technique.

”It is not the answer. ”When he got knocked out the other day against the Tigers, he got off the defensive line quickly but he didn't steady himself enough going into the contact.

“He is used to going into a defensive line with the footy at speed, and not easing up. Whereas defensively, he has now had to get into that repetitive thing of getting off the line quickly, but then you have to steady to go into contact.

NEWCASTLE, AUSTRALIA - JULY 22: Kalyn Ponga of the Knights receives attention after being tackled high by Matthew Lodge of the Roosters during the round 19 NRL match between the Newcastle Knights and the Sydney Roosters at McDonald Jones Stadium, on July 22, 2022, in Newcastle, Australia. (Photo by Matt King/Getty Images)

“Going back to fullback is not going to fix it.''

The Queenslander went off following a head knock in the opening round against the Warriors, though passed his HIA.

Former Knight Alex McKinnon agreed with Lockyer, and believes position should have little to do with it.

Adam O'Brien shouldn't have to worry about where I'm going to play Kalyn,'' McKinnon told the publication.

“The club will do the best thing for Kalyn's welfare, but it gets to a point of getting back out there without fear and understanding the repercussions.

“If the club is going into games with a mindset of wondering where they should play him, well, he shouldn't be playing.

”Adam was confident to move him there, so what has changed?

QLD v NSW - State of Origin Game 3
BRISBANE, AUSTRALIA - JULY 13: Kalyn Ponga of the Maroonsis tackled during game three of the State of Origin Series between the Queensland Maroons and the New South Wales Blues at Suncorp Stadium on July 13, 2022, in Brisbane, Australia. (Photo by Chris Hyde/Getty Images)

“You have to eliminate the thought of a head knock. Otherwise, you're jumping at ghosts.''

The club has doused fears of any early retirement, and likely wouldn't have sent him to Canada on a multi-week trip if that were the case.

There's no timetable on Ponga's return, and is set to remain in North America until his testing is fully complete.