The Aug. 26 fight between Floyd Mayweather (center left) and Conor McGregor (center right) is hardly the first time a fighter has turned boxing into a sideshow. (Gene Blevins/AFP/Getty Images)

Less than two weeks before the big fight, the world champion boxer — perhaps the best ever to lace up a pair of gloves — paid a visit to “The Tonight Show” to promote his upcoming battle, an unorthodox, widely mocked contest between men from different corners of the fight world. The boxer was past his prime and eager for the paycheck, but he promised to put on a show when he stepped into the ring against an accomplished wrestler.

“I wouldn’t take the sport of boxing and disgrace it,” Muhammad Ali said then, as recounted in the 2016 book “Ali vs. Inoki: The Forgotten Fight That Inspired Mixed Martial Arts and Launched Sports Entertainment.” “I wouldn’t pull a fraud on the public.”

Forty-one years later, Ali’s bout with Japanese wrestler Antonio Inoki might have been primarily a cash grab and is still widely regarded as a career low for Ali, but it also set the stage — or at least provided some foreshadowing — for next week’s much-hyped fight between boxer Floyd Mayweather Jr. and mixed martial arts superstar Conor McGregor.

Officially, it’s boxing. It’s sanctioned by the Nevada State Athletic Commission, and as such, the equipment, judges, referee and rules will support that notion. But that’s not why there’s so much buzz surrounding Saturday’s fight in Las Vegas. It may be called boxing on paper, but people will tune in for a spectacle.

While the fighters and promoters are eager to label the bout as historic — the money associated with the fight certainly should break records — the match is just the latest to pit fighters from different disciplines against each other, stoking curiosity and prying open pocketbooks. In many ways, Mayweather and McGregor aren’t breaking new ground; they’re just capitalizing on a time-tested formula.

In 1940, a 45-year-old Jack Dempsey, more than 13 years removed from his last pro fight against Gene Tunney, stepped in the ring against a wrestler named Cowboy Luttrell. “There’s never been a boxer who could beat a good wrestler,” Luttrell reportedly said. “I want to be known as the guy who KO’d Dempsey.’’

He didn’t, and Dempsey, over the hill and desperate for money, pocketed $4,000 for a second-round knockout. He faced two more wrestlers that year. Royce Gracie, a jujitsu master, pummeled a journeyman boxer at UFC 1. Randy Couture, an early UFC star, manhandled boxer James Toney at UFC 118. And perhaps most famously, Ali took on Inoki in a bizarre mixed bout in 1976 — “a carnival sideshow,” Thomas Hauser, the Ali biographer, recently called it.

There are, of course, many other fights that weren’t exactly aboveboard or legitimate sporting competitions. Boxer Chuck Wepner faced Andre the Giant at Shea Stadium the same night Ali took on Inoki in Japan. Wepner, considered the inspiration for “Rocky,” had also tangled with a bear in a pair of charity matches. Even Mayweather has climbed into the ring with non-boxers. He faced Big Show at WrestleMania XXIV, winning with the aid of brass knuckles.

While mixed fighting dates back to the ancient Olympics, there’s a direct line to be drawn from the widely panned Ali-Inoki match to Saturday’s Mayweather-McGregor event. Even if oddsmakers suggest it will be a lopsided affair, giving McGregor little chance to steal a victory, for many, the curiosity factor outweighs actual sporting interests.

“The boxing people at the time really disliked the idea that Muhammad Ali would participate in what they considered a farce. They didn’t see any redeeming value in it,” said Josh Gross, the MMA journalist who wrote “Ali vs. Inoki.”

“ . . . I do think over the time we’re seeing sort of the growth of mixed fighting and the explosion of it as a popular sport, and maybe Ali was a bit ahead of all of us in seeing the potential.”

Bob Arum, the veteran promoter who had a hand in the Ali-Inoki affair, suggests Ali’s motives were a bit simpler: “It was m-o-n-e-y,” he said. “If the money was good, he grabbed it.”

Ali was eight months removed from “The Thrilla in Manila” when he landed in Tokyo to take on Inoki, unknown back in the United States but a relatively big star in Japan. It was billed as the “mixed martial arts championship of the world,” and Ali expected a $6 million payday. But no one was quite sure whether the fight was legitimate or would be scripted. Many oddsmakers refused to take bets on it.

“Ali agreed to do a rehearsed outcome,” Arum recalled. “Then when we got over there, he asked my PR guy, ‘When do we start rehearsals?’ and some moron from the Japanese side who hadn’t been clued in started shouting, ‘What rehearsal?’ That spooked Ali, and he wouldn’t hear about rehearsals after that.”

Ali thought he would put on a show, pummeling Inoki, and eventually draw blood. Ali would plead with the referee to stop the fight, and Inoki would launch a sneak attack and pin Ali.

“But it didn’t happen because Ali decided at the last minute it’d be against the principles of Islam to defraud viewers,” Hauser said. “So at the last minute, they decided to go ahead for real.”

The two sides bickered over the rules and eventually settled on terms that severely limited Inoki. The result was 15 rounds of Inoki almost exclusively fighting from a seated position, crab-walking around the ring and kicking at Ali’s legs. Ali was clearly flummoxed and wasn’t able to throw a single punch until the seventh round.

Ali’s legs were pummeled — they became swollen and developed blood clots — and he only managed to land a couple of punches. Judges ruled the exhibition a split draw. There were no winners. The bout could be seen in more than 130 countries, an unsatisfying viewing experience around the globe.

“It ended up to be the farce that I feared it would be,” Arum said. “There’s just no way a wrestler and a boxer could fight. It was ridiculous.”

Gross says the fight is largely misunderstood, and fight fans at the time had little appreciation for martial arts or what Inoki brought to the table.

“The Ali-Inoki fight was really put in a box as something that should be forgotten,” he said, “kind of a footnote, at best, an embarrassment at worst. Forty years later in a world where mixed-style fighting is popularized and people know what they’re watching, you can view it through a different lens.”

Inoki would go on to face a variety of other fighters, including boxers Wepner and Leon Spinks. Ali had seven mostly forgettable fights before finally retiring. In 1979, he also competed in a pair of exhibition fights in Denmark and an eight-round exhibition against Lyle Alzado, the colorful defensive lineman who was reportedly considering a boxing career.

“I’m not in shape to fight no Joe Frazier or Foreman,” Ali told reporters, according to a Denver Post account. “But I’m in shape for a football player.”

Ali-Inoki offers many parallels to the highly lucrative Mayweather-McGregor affair, though Saturday’s bout is sanctioned and will count toward both fighters’ records. McGregor has a varied skill set but will have to outbox Mayweather, something more experienced pugilists have tried and failed to do for the past two decades.

“I see no way outside of some sort of bizarre intervention, like Floyd falling and breaking his ankle, where this is a competitive fight,” Hauser said. “It’s just not going to happen. If Usain Bolt, as great as he is, was running in the New York City Marathon, he wouldn’t have a chance. The greatest ping-pong player in the world isn’t going to beat Roger Federer, and Conor McGregor isn’t going to beat Floyd Mayweather.”

Boxing match or spectacle, the fight promises to be a pop culture moment as much as a sporting one. It is sure to generate huge money, big interest and draw in a wide range of casual sports fans, even if it manages to offend the more serious devotees of both boxing and MMA. Most will be tuning for a show, the same reason mixed bouts featuring boxers, wrestlers and bears — and, of course, Ali-Inoki — always have sparked some degree of curiosity and fervor.