An under-12s cricket match in which he played almost a quarter of a century ago, however, remains a vivid memory.

The young kid from Scotland, who arrived in the Northern Territory at the age of nine after his father died and his mother remarried, had taken to this unfamiliar new code with a passion. By his own admission, he wasn't much of a batsman, but he was tall and willing and soon earned selection in junior rep teams as a fast bowler.

Anyway, on this particular day, there was some on-field friction with an opposition player, a schoolmate. Afterwards, words were exchanged, then punches. McManus was banned for two games. Even worse, his mum was so upset that she ordered him to find another sport.

She could have had no inkling that decision would change her son's life forever, for better and for worse.

The sporting options in Katherine, a town with a population of fewer than 1000, were limited. There was no soccer, the only sport McManus had played in Scotland.

Confused by the finer points of Australian rules, he signed up for Katherine Bushrangers in a four-team rugby league competition. By 15, he was representing the Northern Territory, and by his final year of high school he was making regular trips to the AIS in Canberra as part of their affiliated-states program.

McManus remembers that the head coach of the AIS, Brian Johnson, "was really good to me". A former premiership-winning fullback who played in 165 first-grade games for St George and Eastern Suburbs, and another 103 games for English club Warrington, Johnson died in 2016 from Alzheimers Disease, aged just 59. His wife, Karen, said later in a Sydney Morning Herald interview: "I suspect it was CTE."

CTE, or Chronic Traumatic Encephalopathy, first emerged as an issue in 2005, when a Nigerian-born neuropathologist, Dr Bennet Omalu, published a research paper in the US that claimed NFL footballers were suffering from early-onset dementia, caused by repeated concussions.

AS Dr Omalu was trying to convince the world that CTE was not a figment of his imagination, on the other side of the world, James McManus was hell-bent on forging a career as a professional rugby league player.

His potential attracted the attention of then Knights development officer Warren Smiles, who signed the 17-year-old outside back to a junior contract, just days before offers arrived from the Brisbane Broncos and North Queensland Cowboys.

Within a week of finishing his HSC, McManus was on a plane to Newcastle, where he progressed quickly through the ranks, from under-18s, to under-20s to reserve grade. Then, two months after his 21st birthday, came a memorable NRL debut, against Canterbury at home, in round one of 2007.

"There's nothing that has made me prouder than playing that first game," he says. "Got a try, got a win. Those memories will always stand out."

McManus played every game for Newcastle in his debut year, a feat he repeated the following season. There were faster, flashier wingers, but few were more consistent or safer under the high ball. And none were braver. "I was a goer," he says. "I didn't have the silky skills, but I gave it everything I had, every game."

For nine seasons, he was one of the first players picked each week in the Newcastle squad. Along the way, he played three State of Origin games for NSW and, in 2013, crossed the stripe 19 times to finish as the NRL's joint leading tryscorer, including four in one game, which equalled the club record.

Then, in round 20 of the 2015 season, during a 52-6 hammering from South Sydney at Stadium Australia that cost coach Rick Stone his job, McManus was helped from the field early in the game, in a state of distress. He would never again pull on a blue-and-red jersey.

HE remembers, vaguely, being in the ambulance, and spending the night in a Sydney hospital. "They give you three words when you first come in, and they ask you to repeat them," he explains. "I couldn't remember them until the following morning."

Days later, he underwent an MRI scan, which revealed scarring on his brain. His career was effectively over, at 29, although the news was not publicly confirmed for several months. "I was pretty filthy," he says.

In hindsight, McManus realises the concussion that forced him to retire was one of many, 25 or more, over a long period of time.

In his first pre-season, the Knights held a full-contact session on Redhead Beach and McManus lost his bearings after a big hit. When training finished, he was told in no uncertain terms to never turn his back on the play.

"That session set the standard," he recalls. "You don't let your teammates down, no matter how badly you're hurt. If I wanted to play first grade, that was the culture."

After another heavy collision, this time in an under-20s match, it wasn't until the video-review session the following week that he had any idea what he had contributed on the field.

Throughout his NRL career, he was rattled regularly by high tackles, or knees or elbow to the head.

"I was able to play through concussions and perform, to a degree," he says. "It was maybe the way I played, as well. I took those early carries, which put me in the firing line."

AFTER full-time sounded several years earlier than expected on his playing career, the Knights offered McManus a role in the club's administration. Behind a brave face, he was struggling.

As well as the recurring headaches and memory lapses, his wife, Eshia, noticed behavioural changes, mood swings. The man she married in 2011 had changed.

"She was the one who forced me into going to the doctors about some of the issues I was struggling with," he says. "Paranoia, anxiety, panic attacks. She could see it was an issue for me."

Eventually McManus took the unprecedented step of launching legal action in 2017 against the Knights and the NRL, seeking compensation of more than $1 million for negligence.

McManus' lawyers claimed he suffered seven concussions in less than five months in 2015, leaving him with post-concussion syndrome, CTE and frontal-lobe damage. They said his health issues include impaired cognitive function and memory, depression, anxiety, lethargy, sleep disturbance and the risk of long-term dementia.

The Sun-Herald reported it had obtained a court document, filed on behalf of the plaintiff, that estimated McManus' life expectancy is just 53.22 years.

After four years of preliminaries, the case was settled out of court last September, after which the NRL announced that it was "resolved in the Knights' favour", whatever that might mean. McManus declined to comment on the legal proceedings, but has no misgivings about heading down that controversial path.

"I never wanted to be the bad guy in all this," he says. "But I've always been one to stand up for myself, and I felt like it was the right thing to do. So I don't have any regrets. I felt that change needed to happen. I held people to account."

SEVEN years after his last game of rugby league, McManus is getting on with life, as best he can. Chatting over a cappuccino at The Barn, in Adamstown, he seems fine, but only those closest to him see the full picture.

"There are times when you feel like you just can't manage, and it's difficult," he says. "There are days when things get really hard. Days when I shut the blinds, put noise-cancelling headphones on, and try to meditate the headaches away. They're the days when I feel like I can't do this any more. My wife and kids help me through."

He describes Eshia as "a saint" and says their two children, eight-year-old Emelyn, and Kyden, six, know there are days when Daddy needs some space.

"The sad thing is my kids," he says, choking up. "Sometimes my daughter will say: 'I wish Daddy never played football'. That's hard to deal with. She sees me having headaches, forgetting things, getting really agitated for no reason.

"The kids know that at times I can't deal with things. They'll be sitting in the car when I'm dropping them off at school, and they'll have something on their mind, but they won't ask me. They'll say: 'That's a Mummy question'. But we're in a really good spot now in terms of being able to manage it."

Every school day, at 2.50pm, Eshia will call to remind him to pick up the kids, just in case.

Since parting company with the Knights, not long after informing them of his intention to sue, McManus has worked in business development with a couple of companies, most recently for the past two years with a Sydney-based firm he says are "very understanding" of his issues.

He is also heavily involved with neurological specialists at Macquarie University, in particular their Biobank and Concussion Connect programs.

"The goal is essentially trying to get to a point where we can better diagnose, better treat, deliver better quality of life ongoing, and hopefully one day a cure," he says. "Some of us are getting intervention and help in our 30s, which is great. But the ones who don't get intervention until their 50s, their issues are a lot worse."

He still stays in contact with "half a dozen" former teammates, two of whom, Darius Boyd and Ryan Stig, have endured their own health battles.

McManus looks back on his rugby league career with mixed emotions and is unsure how he will feel if his son asks to play.

"I've got arthritis in an ankle," the 36-year-old said says. "I've got two bulging discs. I've got three plates in my face. You sort of accept those things. But when your brain changes and you change as a person, you didn't sign up for that."

On the flip side, he appreciates that rugby league has also impacted positively on his life.

"I met my wife here in Newcastle," he says. "My kids are both born and bred here. I wouldn't have had that, if not for football ... I spent a massive chunk of my adult life at the Knights. I moved here when I was 17. I still love the club and want it to do well."

He doesn't watch many games these days, and, if he had his time over, admits he would probably never have played. And maybe he wouldn't have done, if not for that fateful day in Katherine, 25 years ago.

"I was always heaps better at cricket than I was at footy," he says with a rueful smile.

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