Before the game, the children clear what they can of the dirt field in the heart of Port Moresby, the capital of Papua New Guinea. They pick up soda bottle caps, scraps of trash and jagged gravel from between clumps of dead grass.

The players may be small — pants sliding off, jerseys down to their knees, shoelaces straining to hold up too-large boots — but the stakes feel anything but. These are the semifinals, a make-or-break moment for the Taurama Funky Sharks 10-and-under team, taking on the Junior Nomads.

The team’s 29-year-old coach, Gogobe Simi, gives a pep talk about it being “now or never.” The players scurry onto the field, the bullhorn sounds, and the game is on. Written in crude marker on the taped hands of a team waiting to play is a Bible verse, Philippians 4:13. “I can do all things.”

“For us, it’s really serious,” says Samuel David, 17, who is supporting the Sharks.

Rugby league, it is often said, is akin to a religion in Papua New Guinea.

Gold miners from Australia brought the sport — a faster, more aggressive iteration of rugby that split off from the more widely played rugby union in the 1890s — to Papua New Guinea in the 1930s. It has since become a national obsession, a universal pastime and a force for unity in a fragmented place of more than 800 languages and even more tribal groups.

The sport has such an ardent following in Papua New Guinea that Australia is attempting to cement its influence over the country through the game. It has committed to spending 600 million Australian dollars — about $430 million — to give Papua New Guinea its own team in the sport’s premier professional competition, the National Rugby League of Australia.

The deal is not without conditions: Australian officials have described a clause in the agreement that allows for the funding to be pulled and the team to be scrapped should Papua New Guinea enter into a security pact with China.

It’s a soft-power play by Australia over an island nation less than 100 miles to its north that played a vital strategic role in World War II. In recent years, China has invested in infrastructure projects, offered policing assistance and built a gleaming new school. When the rugby league deal was put forward, Papua New Guinea was “within days” of entering into a policing agreement with China, according to an Australian official who spoke on condition of anonymity to discuss matters of intelligence.

It is easy to see why Australia chose rugby league as a vehicle to counter China’s influence.

Gleeful children play the sport for hours on end, barefoot on a dusty stretch of road glistening with specks of glass. They play with plastic bottles stuffed with grass instead of a ball, with rice bags stuffed with newspaper. Rugby jerseys hang in market stalls and from clotheslines, and any television playing a game attracts a rowdy crowd that despairs whenever a power outage renders the screen blank.

“If you’re a politician in P.N.G., you won’t imperil this deal,” the Australian official said. “It would be akin to the mayor of New York doing something to kill the Yankees off.”

Fiona Lahui, mother of the Funky Sharks’ fullback Isaac, put it more simply: “Papua New Guinea has a heart of rugby.”

Bigger dreams

The aspirations of countless young Papua New Guineans playing the sport — and it is a young nation, with a third of its population under the age of 15 — grew in scale with the news that the Papua New Guinea Chiefs are set to make their debut in the Australian league in 2028.

The Chiefs’ roster will be filled with established athletes playing in Australia and some who have come up through Papua New Guinea’s junior leagues, with players up to 19 years old.

“We play for our community, represent our country, then, N.R.L.,” said Alex Endie, 21, who plays on the Southern Sons, a team of young men from 2 Mile, one of Port Moresby’s urban settlements where people live in largely informal dwellings.

The Chiefs’ entry into Australia’s professional league may be too late for Mr. Endie’s cohort, but younger boys in the community will dream bigger for it, said his friend and teammate, Andrew Lohia, 19.

“The small ones, their aim is to be P.N.G. Chiefs in the future,” Mr. Lohia said from the sidelines of an under-17s game, as Mr. Endie shouted to the field, “Play wide, play wide!”

Chiefs players will earn six-figure salaries, a world away from the daily economic realities of most people in Papua New Guinea, which has a gross domestic product per capita of about $3,000 and where 40 percent of residents live in poverty.

Mr. Endie hasn’t been able to finish his studies to become a machinist because his father lost his job and the family can no longer afford his school fees. He and Mr. Lohia instead spend most their days doing what residents call “marketing” — selling grilled sausages and betel nut, a seed chewed as a mild stimulant (each for about 25 cents); and fatty cuts of lamb (for around $1.50) on the roadside.

The country’s prime minister, James Marape, has referred to the National Rugby League team as a “national unity strategy” that can ameliorate ethnic tensions and address the issue of tribal violence. He compared the team’s introduction to South Africa’s post-apartheid victory in the 1995 rugby union World Cup, which brought white and Black fans together.

The opposition has criticized the investment in a sports team over basic infrastructure needs — passable roads, reliable access to water or health care — as a “bread-and-circuses” approach.

“I would have preferred the government spend money on education and health,” said Juliet Amos, whose two sons play with the Funky Sharks. Even so, she said she appreciated the sport’s positive influence on young people with few opportunities who might otherwise resort to petty crime or gang violence.

“Better to have kids here than out there, trying to do stuff like breaking laws,” she said.

‘Natural Fit’

Well before Australia’s overtures, rugby league had been shaping lives in Papua New Guinea.

Angelica Nanege, 30, started playing casual games with other girls as a teenager in the Highlands region deep in the country’s interior. At the time, boys and men would relentlessly mock and heckle them for daring to play.

“Go stay at home, cook for your mama,” they would yell, throwing sticks, stones and water bottles, abuse that lasted for years, she recalled. The girls kept playing and the attitudes toward them slowly changed.

“Now they’re watching and supporting us,” said Ms. Nanege, who has represented Papua New Guinea as a member of the women’s national team, the Papua New Guinea Orchids, and currently plays for the semiprofessional Mount Hagen Eagles.

“We’re not just housewives, we can do anything, just like men,” she said.

On a recent Wednesday morning, at a tin shed gym next to a sweet potato field on the outskirts of Mount Hagen, Ms. Nanege was nursing an injured shoulder from the previous weekend’s game. Her teammates ran through circuits on rusted barbells, holding a plank while singing a children’s song in Tok Pisin.

Part of Australia’s investment is going to an academy program that aims to bridge the gap in opportunities and training with players in Australia and identify and cultivate a generation of homegrown talent of young Papua New Guineans who may eventually fill the ranks of the Chiefs.

Joey Grima, an Australian coach who has been building the pathways program for Papua New Guinea youth for three years, said that even though just a few of the hundreds of boys and girls in the academy will make it to the big leagues, they will nonetheless learn discipline and life skills that will lead to other opportunities.

He speaks proudly of 18 players who last year went back to school after having quit education so that they could participate in the program, which requires academic enrollment. Papua New Guinea has some of the lowest student retention rates in the region.