"Be Water," an ESPN 30 for 30 film chronicling Bruce Lee's life, premieres Sunday at 9 p.m. ET on ESPN.

SOME CAREERS HAVE the good fortune of ending too soon -- they petrify into myth. When Bruce Lee died at 32, on the eve of his first international hit, "Enter the Dragon," whatever he might have become lapsed into what might have been, into the realm of rumor and wish fulfillment and conjecture.

And perhaps no question about Lee is as trivial yet ardently pursued as this: Could Bruce Lee win a real fight? It's in some ways predictable that fans hungrily debate the skills of the man who refined and mainstreamed the martial arts film as we know it. Few actors have ever exuded as much physical charisma on screen as Lee. He makes you want to believe he's the real thing. When watching his films, one feels the nostalgist's urge to vindicate old affections. If, off screen, it turned out he wasn't so dangerous after all, so masterful, we'd feel duped. He left us longing -- in that way he was one of the great actors of his era. And so there are hours of Zapruder-esque YouTube videos dedicated to Lee's fighting prowess, bottomless Reddit threads obsessed with this nerdy, needy question.

Last summer, Quentin Tarantino, in his revisionist odyssey "Once Upon a Time in Hollywood," added his impudent voice to the debate when he depicted Lee, played by actor and martial artist Mike Moh, as a vainglorious braggart who gets into a fight with Brad Pitt's Cliff Booth, a stuntman and former Green Beret. The portrayal angered many. Lee's daughter, Shannon, accused the director of replicating the racist contempt her father suffered while he was alive. "He was continuously marginalized and treated like kind of a nuisance of a human being by white Hollywood," she said, "which is how he's treated in the film."

The fight in "OUATIH" is partly based on Lee's first meeting with Gene LeBell, a two-time national champion judoka and legendary Hollywood stuntman who is credited with popularizing grappling in North America. They were introduced on the set of "The Green Hornet" in 1966, where LeBell promptly scooped up the not-yet-iconic actor, tossed him over his shoulders and carried him around the set in a fireman's lift.

Lee was not amused. But LeBell laughed anyway. He was introducing himself, in his way, as a fellow martial artist, not challenging Lee, who was frequently called out by daring stuntmen on his movie sets.

Lee and LeBell forged a friendship away from the set, training together for about a year in the late 1960s. (Decades later, LeBell would scandalize Lee's public by insisting his pupil Ronda Rousey could kick Lee's ass.) It was during those sessions that Lee started to incorporate grappling into his style. He would later use submission holds to finish opponents in his fight scenes, like his classic guillotine choke of Chuck Norris in "The Way of the Dragon." In addition to LeBell, Lee worked for years with the likes of Norris and Joe Lewis, two of the most celebrated non-boxing fighters of their day. Before he became an action star, Norris was the world middleweight karate champion from 1968 to 1974. Lewis won what is regarded as both the first kickboxing match in the U.S. and the bridge between the karate point fighting era and the full-contact kickboxing we know today.

UFC welterweight Stephen "Wonderboy" Thompson, unusual among prominent mixed martial artists for being a karate stylist, amassed a 57-0 record as a professional and amateur kickboxer before joining the UFC. He knew Lewis personally and says Lewis told him one of the hardest kicks he'd ever endured was from Bruce Lee. Lewis was a heavyweight kickboxer; Lee was 5-foot-8 and weighed less than 150 pounds.

"You can't tell me that Bruce Lee is not a hard guy, wasn't a good martial artist, wasn't a good fighter, if you got guys like Joe telling me that," Thompson says.

Lewis, who died in 2012, said it was under Lee's tutelage that he broke with karate point fighting once and for all and transitioned into full-contact fighting. In 1970, Lewis faced Greg Baines in a full-contact match that didn't have a name until the ring announcer, in an accidental but successful bid to make history, announced the two men as kickboxers.

The fact that fighters like Lewis trained with Lee before he was Bruce Lee -- learned from and taught him, and took him seriously -- provides a great deal of evidence as to what kind of fighter Lee might have been. The equivalent today of what Lee was doing back then, working with real fighters as a peer, would be like watching actor Jason Statham sparring in earnest with UFC light heavyweight champ Jon Jones; it would never happen. No one would cover Statham's insurance.

Contemporary fighters, no doubt overawed by a man they consider the progenitor of their vocations, speak of Lee worshipfully. In 2014, Conor McGregor insisted that Lee would be a world champion in the UFC. And before his fight against Floyd Mayweather Jr. in 2017, McGregor cited Lee's philosophy as an inspiration for his crossover attempt into boxing. "That's what a true martial artist can do -- they can adapt under any circumstance," McGregor said. "Bruce Lee said, 'Be like water.' When water enters a cup, it becomes the cup."

And fighters who think of themselves as Lee's fellow travelers aren't limited to MMA. In a 1982 Playboy interview, Sugar Ray Leonard suggested he perfected his jab by watching Lee. And Manny Pacquiao, asked by The New York Times to describe his fighting style, said simply, "Like Bruce Lee."

"I think if he [Lee] was in his prime today, he would be where Conor McGregor is now," Thompson says. "He would be that guy."

IT IS WELL DOCUMENTED that as a teenage protégé of the legendary Yip Man, a master of Wing Chun Kung Fu -- which is characterized by its economy and rapid, direct hand parrying and striking -- Lee fought frequently on the roofs and back alleys of Hong Kong. Still, he has only three recorded fights on his "record," as it were. Each was instrumental in shaping his views of fighting.

Lee won an interschool boxing tournament in Hong Kong in 1958 while deploying some mixture of Wing Chun and rudimentary Western boxing he tried to pick up by himself in preparation for the contest. He easily bested Gary Elms, the city champion in that weight division the previous three years, knocking Elms down three times in the three-round bout.

It was Lee's first encounter with Western boxing and his first time competing in a rules-based tournament instead of street fighting. According to Lee biographer Matthew Polly, Lee disliked the experience. He felt the padded gloves stifled his power; he couldn't quite find Elms the way he wanted. The fight planted the first seed of doubt about the effectiveness of Wing Chun's orthodoxy in Lee's mind and left him with a lifelong aversion to tournament fighting and an obsession with the problems of fixed styles.

Years later, after he moved to Seattle and began training others in martial arts, Lee would often boast that his Wing Chun was the preeminent fighting style, leading to frequent arguments and challenges from adepts of other forms. One such argument resulted in the second-most storied fight of Lee's career, a showdown with Yoichi Nakachi, a Japanese karate black belt. After days of taunting, the two decided to settle their grudge at a local YMCA. The fight ended in 11 seconds. A flurry of punches from Lee sent Yoichi reeling to the floor, where Lee dashed in to kick his opponent in the head, knocking him out cold.

A similar incident led to the most important fight of Lee's career, in Oakland in 1964. Ed Parker, the founder of American Kenpo and perhaps the country's first karate entrepreneur, invited Lee to the Long Beach International Karate Championships. There, Lee gave a scintillating performance, demonstrating his one-inch punch, finger pushups and kung fu techniques. But he also gave a lecture, asserting the supremacy of the individual practitioner over the rigid demands of style and denouncing instructors for enforcing sclerotic katas on their apprentices. In effect, Lee undermined the very tradition of martial arts pedagogy that had lasted for centuries. His audience was outraged.

Word of his exploits traveled back north to the Bay Area. Weeks later, at another demonstration in San Francisco where he mocked traditional kung fu, Lee issued what was understood (perhaps mistakenly) as an open challenge to any practitioner in Chinatown.

Wong Jack Man, a recent émigré from Hong Kong who, like Lee, was 23 and trying to make a name for himself and open his own school, took Lee up on his dare. After weeks of negotiating the time and place and rules, Wong and a handful of friends drove to Lee's training and teaching studio in Oakland. Lee was attended by his wife, Linda, and his business partner, James Lee. What followed over the next few minutes remains a matter of dispute. Polly says that researching the details of the fight took nearly a year.

A composite of all the various accounts, eyewitness testimony, hearsay and urban legend thrice removed, transmuted by time and distorted by Lee's staggering posthumous celebrity, amounts to something like the following: Wong Jack Man extended a hand in what he said was a preliminary greeting (think touching gloves before a boxing match), Lee dispensed with that pleasantry and rushed forward, sending his opponent back. Lee was eager to re-create the 11-second knockout of Yoichi and to fulfill one of the dictums he had learned from street fighting: End things quickly. But Wong Jack Man, a talented kung fu stylist in his own right, was highly evasive -- so evasive, in fact, that he briefly turned his back on Lee to get away. Eventually, Wong Jack Man wheeled on Lee, striking a blow to his neck. Lee pushed his attack harder, and Wong Jack Man tripped on a slightly elevated ledge on the studio floor, allowing Lee to pounce on him and land a salvo of punches before the two men were pulled apart.

Lee won, but neither man looked good. The three-minute fight left Lee winded and deeply troubled. He feared the limits of Wing Chun had finally been exposed. He didn't know what to do with an opponent determined to keep him at range instead of attacking, and he was disappointed with his stamina.

That night untethered Lee once and for all from the constraints of Wing Chun or any other single style.

"In the old days, you'd do what your teacher tells you, because it's a 500-year tradition and you're supposed to keep the tradition going," Polly says. "Lee was the first person to come out and explicitly say, 'Traditions and styles are stupid. All that matters is what works for you.' And people hated him for it at the time. It wasn't an easy position to take."

Like Warhol and Ali and other '60s iconoclasts, Lee's rupture with tradition would prove seismic. His new ideas about martial arts -- that it had to be syncretic, streamlined, bespoke, honed for combat instead of aesthetics, paved the way for mixed martial arts, an embryonic form of which he practiced when he developed his own personal form, Jeet Kune Do.

When people describe Lee as the father of MMA, as UFC president Dana White has, for example, that is what they mean.

"HE WAS YEARS ahead of his time," says Dan Inosanto, a disciple, training partner and close friend of Lee's who still teaches Jeet Kune Do. Inosanto has given occasional lessons to fighters the caliber of Anderson Silva, who is widely considered among the greatest MMA fighters of all time. Inosanto has intimate knowledge of Lee's techniques and philosophy. "I've been knocked down and hurt by him more than any human being," he says, laughing.

Both Inosanto (from firsthand experience) and Polly (from numerous interviews) describe Lee as remarkably fast and intuitive. He was a "kinetic genius," says Polly, going on to describe Lee's quickness and uncanny anticipation in much the same terms opponents use to describe Floyd Mayweather Jr. Inosanto believes Lee's training methods helped mainstream the adoption of focus gloves, now used throughout the fighting world to sharpen accuracy and timing.

Part of what contributes to the idea that Lee was a fighter and visionary, not just an actor-martial artist like, say, Steven Seagal or Jean-Claude Van Damme, is that even in his movies, Lee choreographed with a fighter's brain. Thompson recently gave an interview for GQ in which he broke down the plausibility of various fight scenes. He lauded not just Lee's technique but also his understanding of how combat works. Lee wins a fight in "The Way of the Dragon" by first front-kicking an opponent's forward hand and then replicating the movement, only to uncurl and extend his leg into a head kick. Today's mixed martial artists would call that a question-mark kick, a staple of the world's most advanced strikers.

But these are movies. Moh, the actor who played Lee in "OUATIH," is a fifth-degree black belt in taekwondo. He also has trained in a little bit of Brazilian jiu-jitsu. (One dabbles in BJJ the way one dabbles in poetry: You hope no one ever asks to see the proof.) He draws a hard line between martial arts and fighting. "For me to be like, 'Oh, I could take my fifth-degree black belt and beat somebody up,' I think that's absurd," Moh says. "Obviously I spar and I train, but would I put myself in the Octagon? No, I would need years and years of specific training just to fight."

The answer to the question of whether Lee was a real fighter would require us to wrench him out of his context. Since the UFC debuted in 1993, mixed martial arts have undergone a dramatic evolution. The development of MMA around the world forced a lot of martial arts theorizing and teaching to melt in the flash fire of real fighting. BJJ, for example -- unglamorous, intricate, brutal and exacting -- has ascended as the indispensable martial art. It's almost impossible to succeed as a professional mixed martial artist without at least a solid BJJ foundation. The karate point fighting tournaments that Norris thrived in, Lee scorned and Lewis eventually consigned to obsolescence some 50 years ago are unrecognizable as fighting now.

What we're left with is hero worship. That's why this otherwise meaningless question matters. "Asian fans are probably more protective of Bruce Lee and his legacy because he became a global icon and he seemed to do it on his own terms," The New Yorker's Hua Hsu wrote in an email to ESPN. "He became a movie star by confounding expectations and stereotypes, not by playing into them. And it wasn't just his physicality, which differed from the perception of Asians as cerebral and passive. It was his arrogance and vanity -- the fact that he didn't just feel like he belonged in Hollywood's upper strata but that they could learn from him too."

The true fighting abilities of Lee's martial artist-actor successors like Seagal and Van Damme and Jackie Chan are questioned all the time, typically with a sense of humor (save for the subjects of the query). But with Lee, it's different.

"Bruce Lee is the reason that many in my generation of martial artists started martial arts," Polly says. "He's not just a celebrity. He's a patron saint. Martial arts is quasi-religious, and when you're insulting Bruce Lee, it's like insulting someone's iconic saint hero, almost a religious figure."

The main account of Lee's fight against Noichi Yakachi comes from Jesse Glover's book "Bruce Lee: Between Wing Chun and Jeet Kune Do." Glover, who died in 2012, was Lee's first student and later a highly respected martial artist. In Glover's description of the fight, Lee hit Noichi with a double punch that "lifted the man completely off the floor and sent him flying 6 feet through the air."

Polly's vigorously researched biography is not immune to that sort of mythopoeia either. He too repeats the "6 feet through the air" figure about Yoichi. And in another scene, a 230-pound skeptic who asks to see Lee's famous one-inch punch flies "8 feet" through the air when our hero demonstrates the technique on him. These are signs and wonders, the hysteria of the acolyte.

The truth is, in many ways, prizefighting is directly opposed to the ideals of traditional martial arts, which stress inward development, combat against the unruly and opaque self. "The reason we learn how to train, how to kick, punch and fight," Moh constantly tells his beginners, "is so that we never have to."

LeBell also makes this point. While he has the utmost respect for Lee as a martial artist, he believes that the only thing that makes one a fighter is fighting other professionals, and often. "You can hit a punching bag all you want. Unless somebody is hitting back at you, you don't become what I consider adequate," LeBell says. "Martial arts is a great exercise. It gives you ideas about what to do. But if you want to be a professional, you fight."

DESPITE THE BRUISED sensibilities of Lee's fans around the world, Bruce Lee doesn't actually lose his fight in "Once Upon a Time in Hollywood." Tarantino stops several seconds short of the heedless revisionism he flaunts in the rest of his film. The Lee of "OUATIH" is cocky, hotheaded and easily goaded by Cliff Booth after he laughs at Lee's claim that he would "cripple" Cassius Clay. (In a strange anachronism, not remarked upon, everyone in the scene uses the name Cassius Clay. "The Green Hornet" aired on television some two years after Clay renamed himself Muhammad Ali. "OUATIH" really is a fairy tale of reaction.)

Lee and Booth agree to a best-of-three, the winner of each round the man who claims the first fall. Lee floors Booth with a flying kick, exactly the kind of maneuver the real Lee would deride as a flourish unfit for combat. But this Lee steps away jauntily, taking the bait when Booth invites him to try it again. Lee does, only to be snatched out of the air and heaved against a car, cratering its passenger-side door.

Notably, Tarantino has Booth remembering this fight in a daytime reverie, adding yet more doubt to how much of the scene we should believe is true and how much of it is blurred in the honeyed sunlit glow of Booth's self-aggrandizing memory.

The third round is a close-run thing. Booth is the larger man, and he's not without skill. It's unclear who is going to take it before the two men are interrupted. Obviously, part of what rankles some about the scene is the racial subtext. "When Tarantino has a white guy beat up the iconic Asian badass, it feels like there's something more going on than if he had been beating up, I don't know, Steven Seagal or John Wayne," Polly says. "Bruce Lee represents Asian strength and in a society where Asian males are portrayed as weak."

But somewhere underneath that is the tremor of fantasy rubbing up against the ambiguity and unpredictability of human performance. Despite its obvious choreography, Lee and Booth's fight is tense, almost startlingly so given the dreamland setting it takes place in. Its faithfulness to what a fight between two such men might feel like is exactly what the real Bruce Lee strove to achieve in his own work.

And that surprising realness, despite the audacity of the whole sequence, is another source of its controversy. Tarantino forces some encounter between our idea of Bruce Lee the icon and, however narrowly or fleetingly glimpsed, however clumsy, an image of Bruce Lee the man, the fighter capable of rashness, capable of losing. In that meeting, myth quickens to flesh, sweats and trembles.