Anthony Joshua of Great Britain celebrates after defeating Dominic Breazeale of The USA during their IBF World Heavyweight Championship bout at The O2 Arena on June 25, 2016 in London, England.

Anthony Joshua is a former Olympic gold medalist for Britain, undefeated in his pro career and the current IBF champion. On Saturday, he’s scheduled to fight Ukrainian Wladimir Klitschko before 90,000 fans at Wembley Stadium in London, and a victory would unify three of boxing’s fractured titles and potentially make him the defining heavyweight of his time.

But the implications of a Joshua victory would reverberate well beyond his own career, solidifying what has been a profound geographic shift in boxing. Joshua, 27, could emerge as a global superstar without so much as setting foot in an American ring. Even 15 years ago, this kind of achievement would be unthinkable. Yet Joshua’s promoters, at least so far, seem unconcerned about establishing him in the U.S.

It’s only the latest evidence that America’s hold on boxing – from the grass roots, to our amateur and Olympic programs, and finally the professional domain – is slipping away.

For more than 60 years, the cultural impact of boxing has moved in lockstep with the champions it produces in the heavyweight division, from Floyd Patterson, Muhammad Ali, Joe Frazier, George Foreman and Leon Spinks on down to Mike Tyson. All except Tyson entered the professional ranks riding the wave of Olympic glory. (Klitschko, now 41, won gold in 1996.)

Saturday’s bout is perhaps the most anticipated heavyweight battle since Lennox Lewis defeated Tyson in Memphis, Tennessee, back on June 8, 2002. If Joshua succeeds, the impact could be felt in the boxing world for a generation. He has won each of his 18 pro bouts by knockout, and a win over Klitschko, 64-4 and a former world champion, would not only reclaim a place for the heavyweight champion in the consciousness of sports but would also demonstrate how thoroughly the United Kingdom, the country Joshua fights for, has entered a golden age of boxing.

One example occurred on Dec. 10, 2016, before a deafening crowd at Manchester Arena, when Kal Yafai, a 112-pound British fighter, defeated Luis Concepcion of Panama by unanimous decision to win the WBA super flyweight title. While attracting little fanfare in America, the fight’s significance on boxing globally was huge. With Yafai’s victory, the United Kingdom had 13 current titleholders and, despite having one-fifth the population, more world champions than the United States has had at one time in more than a century.

Boxing was once the most visceral example of the rags-to-riches American dream. Yet today, that dream is coming to life more frequently in the United Kingdom. For instance, a nontitle fight on March 4 between heavyweights Tony Bellew and David Haye took place in London’s sold-out O2 Arena with a massive domestic pay-per-view audience that enabled both fighters to receive purses well into seven figures. American viewership had no bearing on the calculus of making it a success.

Contrast that with the November 2016 bout in Las Vegas between Andre Ward and Sergey Kovalev, two undefeated light heavyweights in a pick ’em fight, both comfortably in the discussion of boxing’s top five pound-for-pound. But the match generated dismal financial numbers despite a considerable publicity push by HBO, boxing’s pre-eminent network.

Steve Farhood, a Showtime announcer and former editor-in-chief of The Ring, speculated about what that means for a potential match between Joshua and the leading contender in the U.S.

“Should Joshua be successful [against Klitschko], would Joshua’s people even feel the need to expose him in America?” he said. “We have a young undefeated heavyweight champion in Deontay Wilder who’s knocked out nearly everybody he’s faced. If there’s a unification between Joshua and Wilder, there’s no guarantee it would even need to be in America. Economically, it may not even be necessary anymore.

“When Tyson fought [British champion] Frank Bruno, it happened in America. Lennox Lewis had all his major fights in America. Economically, that dynamic is changing,” he said.

Farhood said the Floyd Mayweather Jr. vs. Manny Pacquiao “Fight of the Century,” held in Las Vegas in 2015, “showed us that in terms of pay-per-view audience, the biggest audience is still going to be here in the United States. We’re five times the size. But in terms of live gate? They may have surpassed us over there. For Joshua and Wilder to be a massive showdown, it’s Wilder that has to keep up his end of the bargain.”

Long before he became a viral sensation with his Boxing Lessons with Eric Kelly, the New York trainer fought his way off the crack-ravaged streets of Brooklyn, New York, in the late 1980s to become a four-time national boxing champion. By 2000, he was ranked fourth in the world as an amateur and had secured a spot as an alternate on the U.S. Olympic boxing team.

Violence outside the ring ended Kelly’s ring career before he had a chance to turn professional. But he credits the sport with saving his life, and now, after his video’s success and subsequent work with Vice, allowing him to live his dream by opening a boxing gym in the South Bronx.

I asked Kelly how boxing has changed in America.

“In 1976, America had arguably the greatest Olympic team ever. The face of that squad was Sugar Ray Leonard. How many kids did he inspire? Well, you saw how many he inspired when 1984’s team won almost everything and gave us Evander Holyfield, Mark Breland, Pernell Whitaker, Tyrell Biggs. Those fighters and Sugar Ray inspired Roy Jones Jr., the best fighter at the 1988 games. At the 1992 games, Oscar De La Hoya had the biggest story coming out of the Olympics, winning a gold medal for the U.S. and his dead mother. Andre Ward, our last Olympic gold medalist from 2004 — look who inspired him the most. Roy Jones Jr. was his hero. Who’ve we had since Ward?”

Not only have no American men won an Olympic gold medal since Ward, but at the 2012 London Games, American male boxers came home with no medals at all. During the lead-up to the 2016 Rio de Janeiro Games, the American media were so desperate for a positive spin on Team USA’s chances that they pushed their infomercials of American male boxers most likely to stand on the podium with any medal.

Kelly traced the explanation back to the ground level.

“I moved to Brooklyn in 1988,” Kelly said. “I was 8 years old, and when I’d go over to Prospect Park to play, people were shooting people in broad daylight in front of me. Crack vials were everywhere in the park and in the streets. All different colors. Yellow, green, orange, red crack vials under your sneakers.”

A mile away from where Kelly grew up was the Brownsville neighborhood, the home of several of the greatest fighters America has ever produced: Patterson, Tyson, Breland, Riddick Bowe, Shannon Briggs. They all found their way off of some of America’s roughest streets through boxing. Kelly survived the same way.

“How many boxing gyms were out there for you to choose from back then?” I ask. “A dozen?”

“A dozen?” Kelly growls. “You had a dozen just in Brooklyn.”

And now?

“Geez,” he moans. “Maybe two.”

“There are fewer gyms,” said Kurt Emhoff, an attorney and manager who has worked with more than 10 professional champions. “The cost of insurance, the rising rents, the competition and proliferation of fitness gyms have all gutted the neighborhood rec centers and boxing gyms.

“The downward spiral also happened when boxing left broadcast networks for HBO and Showtime,” he continued. “You don’t see amateur boxing on TV anymore. It used to be a mainstay in the ’70s and ’80s. Even the Olympics is hidden away on some satellite network, while swimming and gymnastics are on prime time.

“I don’t think you can ignore the war on drugs and the resulting mass incarceration across the U.S. either. Boxing gets its talent pool from the inner city, not the suburbs. There were less than half a million incarcerated Americans in 1980, and that has increased by a multiple of five over the last 30-plus years, with the inner cities being disproportionately represented in that population. Fewer gyms, less mainstream exposure, more aggressive incarceration of the areas where the talent pool is. Not surprising to see where we’re at.”

I reached out via email and phone to Michael McAtee, USA Boxing’s executive director, for comment about the state of amateur boxing and never received a reply.

But Kelly has a similar view of the causes.

“By 2000, kids around me in boxing gyms, on the way up, they heard all the stories of what happened to the great fighters losing everything,” he says. “That’s when they started going to other sports. Basketball. Football. They got sponsorships in those sports. They got college scholarships. Boxing didn’t and still doesn’t have none of that. And boxing has always been dirty. There were a lot more spots in those other sports for them to land and make real money and keep that money, too.’

“Plus, and here’s the thing: When you’re playing basketball or football at a high level, you’re guaranteed to be seen on CBS, Fox, NBC, major TV coverage. They’re gonna be in newspapers. They’re gonna be on SportsCenter. They’re gonna stay in America’s eyes.

“As we speak, there’s a professional boxing match going on right now. Somebody is in their corner waiting for Round 9. Somebody’s mouth is full of blood with tears in their eyes as we speak. Sweat is pouring down all over their body while they’re fighting for their life, and nobody knows anything about it. It’s not televised. It’s not reported.”

When Muhammad Ali and Joe Frazier fought for the world heavyweight championship in 1971, they each earned a record $2.5 million guaranteed purse for one night’s work. Compare that to Carl Yastrzemski, Major League Baseball’s highest-paid player, earning $167,000 for a season of work. Dick Butkus earned $50,000 in the NFL. Seven years later, an over-the-hill Ali fought Leon Spinks in front of 63,000 fans in New Orleans Superdome and millions more watched on TV.

Even the few boxing gyms that remain aren’t venues for producing champions, Kelly says. He points to the example of New York’s famed Gleason’s Gym, which famously trained Jake LaMotta and Roberto Duran.

“Sure, Gleason’s is still around, but you and I both know Gleason’s ain’t Gleason’s no more. Not if you wanna be a killer in the sport,” Kelly says. “If you want a good workout or hit the mitts? Sure. But if you wanna become a killer and be surrounded by killers? Nah. Iron sharpens iron. You can’t sharpen iron with the plastic credit cards of celebrities and bankers.

“Most of the time I walk into Gleason’s, chances are, me alone, I got more amateur trophies and accomplishments than the entire gym put together.”

Kelly landed at Church Street Gym, where his video training of well-heeled clients made him famous.

“Church Street isn’t a real gym” either, Kelly says. “But they’re all extinct in Manhattan now. At the end of the day, money talks. When I got there, Church Street was totally white-collar. The only way I could hope to make a living was being in a white-collar gym.”

He’s opening his own gym in the South Bronx in May. But he’s frank that “at the end of the day, if I wanna keep the lights on, I’m gonna have to cater to the white-collar crowd, too. It’s sorta like I’m becoming the demise of what boxing used to be for kids like I was. Because, what else you gonna do?

“That’s capitalism. Let that marinate for you.”

Over in the United Kingdom, the successes of Lewis, Naseem Hamed, Amir Khan, Kell Brook, and now Joshua are all examples of how boxing’s dream has relocated across the Atlantic.

Terry Edwards, Great Britain’s former Olympic boxing coach, oversaw massive improvement and funding at the amateur level. He ran an elite squad of boxers, based full time at the Sheffield Institute for Sport, that ultimately led to eight British boxers qualifying for the 2008 Beijing Games. Three of them won medals, including James Degale taking home gold. Five of those boxers went on to professional careers. The country recognized Edwards’ achievement in 2008 when he was named a Member of the Most Excellent Order of the British Empire for his services to boxing.

At the London Games in 2012, Great Britain led the world with three boxing gold medals and tied Ukraine for overall medals with five. Joshua, named Amateur Boxer of the Year by the Boxing Writers Club of Great Britain, fulfilled expectations when he took home super heavyweight gold before a home crowd.

After a troubled youth, Joshua, the child of Nigerian parents, began fighting at 18. His enormous talent coupled with a personal transformation enabled him to win Olympic gold only four years after lacing up his first pair of gloves.

That quick success has continued in the professional ranks, where no opponent has survived past the seventh round. With less than two hours in the ring as a professional, Joshua is already a menacing, and popular, champion. After the announcement that the Klitschko fight had sold 90,000 seats in Wembley Stadium, his promoter bragged he could have sold double that amount. Joshua has already shared his desire to become boxing’s first billionaire.

Back in the United States, the most lucrative fight on the horizon is a cynical farce between Mayweather and mixed martial artist Conor McGregor, appropriately framed by a Las Vegas skyline.

“Watch me take over boxing,” McGregor said at New York’s Madison Square Garden on St. Patrick’s Day. “Trust me on that. No one in this game knows what’s coming. I’m going to shock the whole God damn world.”

McGregor, making his professional boxing debut against one of boxing’s all-time greatest fighters, would be a prodigious underdog to win even a round against Mayweather. Which isn’t to say someone won’t make a boatload of money.

As that “fight” demonstrates, the central issue isn’t that boxing in America is sick. It’s that, rather than look for a cure, the sport’s enablers have become accustomed to the disease.

The architect of much of the United Kingdom’s enormous success with boxing is Matchroom Sport’s Group managing director, Eddie Hearn, Joshua’s 37-year-old promoter. Hearn recently talked with Yahoo Sports’ Chris Mannix on a podcast about Joshua, boxing’s success in the U.K. and his future ambitions.

“This is a gamble before our time, but it’s a calculated gamble. … We never expected to fight Wladimir Klitschko in our 19th fight. But the opportunity has presented itself” Hearn said. “We know the risks, and it is a 50-50 fight. But it’s a gamble to become the unified heavyweight champion of the world. And it’s a gamble to take Anthony Joshua to new levels and, I believe, make Anthony Joshua the No. 1 star in world boxing. This is the kind of fight that will set you well on the way to achieving that goal.”

Hearn laid out his plans for the future:

“Our relationships with HBO and Showtime are extremely positive. They see what we’re doing in the U.K. I think there’s a desire to give me a shot. … If I was a promoter in America, I would be very afraid of me coming over here to promote.”

“As much as Americans may think it belongs to them, this isn’t baseball,” HBO’s star commentator Jim Lampley told me. “It’s still a sport conducted by a set of rules written up by a British guy. Joshua is on the doorstep of showing the world how special it is to be a champion there today compared to almost anywhere else right now. The dominance of the heavyweight division was once thought to be the property of the U.S. It only stands to reason if one country, like the U.K., establishes itself as the epicenter of boxing talent globally right now, that that’s where you’d look for the next great heavyweight champ.

“Whether it was Jack Johnson, Jack Dempsey, Joe Louis, Ali, Foreman or Tyson, we always had a dominant U.S. fighter at the top of boxing’s pyramid. It was vitally important to the development of American boxing. We don’t have that anymore.”

What have Americans really lost with boxing’s increased irrelevance back home?

Look back to when Joe Louis fought his rematch against Nazi Germany’s Max Schmeling on June 22, 1938. It was likely the first time America had ever collectively gotten behind an African-American man. Both of Louis’ parents were the children of slaves. The Ku Klux Klan had driven his parents from Alabama to Detroit when he was 12. His mother tried to get the young Joe Louis Barrow interested in the violin. So Louis, according to legend, carried his gloves inside his violin case and secretly entered a boxing gym.

As Louis entered the ring against Schmeling, a 10-year-old Maya Angelou listened on the radio in her uncle’s store in Arkansas and later wrote:

“My race groaned. It was our people falling. It was another lynching, yet another black man hanging on a tree … this might be the end of the world. If Joe lost, we were back in slavery and beyond help. It would all be true, the accusations that we were lower types of human beings. Only a little higher than apes.”

But Louis won. And Angelou wrote better than anyone what that meant:

“Champion of the world. A Black boy. Some Black mother’s son.”

For a century, boxing offered the promise of deliverance to many of America’s forgotten children born to its most troubled cities. Today, many of those same children see a faded American myth.

In sickness or in health, boxing offers as haunting a reflection of America as it ever did. Once, it gave young men a chance to rise, to stand, to be seen, not just as the best of America, but of the world. Now, that dream has been passed along to another young man, but this one will fight in London and represent another country’s story of rise and redemption.