The moment will live forever, the sound as much as the fury that followed, more than 56,000 people exhaling as one, then unleashing a roar unlike any in mixed martial arts history. Holly Holm had done the impossible, vanquishing the queen of MMA in a little over one round, dominating an encounter with a fighter few had managed to last more than a single minute with.

The hammerfists in the aftermath were fine, but it was the kick to Ronda Rousey's neck that made her immortal. 

More than three years later, it's barely possible to remember the tumult this caused at the time, to recall the extent of Rousey's domination, the sheer unlikelihood of her eventual demise.

This was before a subsequent self-imposed exile from public life, before the deer-in-the-headlights performance against Amanda Nunes, prior to Rousey cutting and running to WWE where the tricky matter of winning bouts could be decided in a conference room beforehand. 

There are two distinct Rouseys—the one before Holm and the one after. One left shin changed the trajectory not just for two fighters, but also for an entire sport.

"She is a world championship boxer. A world championship kickboxer," UFC announcer Joe Rogan said of Holm before the 2015 fight at Docklands Stadium in Melbourne, Australia. "She has undeniable striking pedigree. Undeniable success rate inside the Octagon. And she is a woman who is a real championship-level fighter. The question is, can she rise to the occasion fighting the greatest female fighter the world has ever known." 

In retrospect, it's wild hyperbole—but it wasn't atypical for the time. Just weeks before the fight, Rousey was on the cover of The Ring Magazine, as the Bible of boxing speculated about her potential in the squared circle. It was a given that she would dispatch any of the women UFC could find to fight her, to the point fans and media began debating how she would do against men in her weight class, a fantasy Rousey herself was more than happy to indulge.

Rouseymania was running wild. Almost no one counted on Holm, a calm, country tomboy who ending up being the perfect foil to her opponent's Hollywood glitz and manic aggressiveness. 

The kick to the side of Rousey's dome wasn't born in the months prior to the fight. It was 18 years in the making, starting the moment Holm walked into Mike Winkeljohn's gym in Albuquerque, New Mexico.

It was a cardio kickboxing class, designed to get the heart rate going. Any applicability to the world of self defense was purely coincidental. But Winkeljohn noticed the young blonde girl with the ponytail eying the sparring that was going on elsewhere in the gym. It wasn't long before she requested a turn in the hot seat.

"Her first day in sparring, the first time she got hit, she got pissed and came right back," he says. "It tells you she had the willingness. It's easy to sit at home, drinking and beer with your buddies and talk about what you would do. But to actually deal with someone hitting you is a whole different story. I knew she was a fighter at that moment."

It was an odd pairing from the start. A gruff former fighter himself, Winkeljohn isn't known for his patience or gentle manners. More than that, he wasn't even sure Holm should be fighting, let alone want to be a part of it. 

"I was kind of traditional," Winkeljohn says. "I didn't want to have women fight or see women get hit. I won't lie. But what do you do when someone wants to live their dream?"

Holm, he found out, had grown up in Bosky Farms outside of town, running around with older brothers, shooting guns, climbing trees and roughhousing with the best of them. Plus, the more he worked with her, the more he realized she just had it, that natural ability to meet fire with fire, to respond to violence with a cool, calculating calm, to remember her training and the battle plan at the point of contact.

All those things, as simple as they sound, are actually quite rare, even among those training to be an elite fighter. So, it wasn't long before Winkeljohn went from questioning his involvement with Holm's career to imagining a string of world titles in two sports.

He was wrong. She ended up taking home championships in three. Soon the biggest challenge was finding anyone to fight her at all. Established fighters didn't want to come to Albuquerque to face the young prospect, but neither did they want to bring her to their neck of the woods and face potential embarrassment in their own back yards. 

Winkeljohn and manager Lenny Fresquez were forced to ramp up Holm's level of competition early, even bringing in women boxing's wrecking ball Christy Martin to face her just three years into her career.

"We had to bring the biggest and the baddest to Albuquerque," he says. "Everybody thought we were crazy, but I was watching her fights and she had no footwork. It was all toughwoman stuff. So we started working footwork and Holly earned her reputation with it.

"Christie threw a punch at Holly that missed badly and she got herself tangled in the ropes. Holly turned to me and kind of smiled and then went on to just pick her apart."

It was a moment that came back to Winkeljohn 10 years later in the hours before the Rousey fight.

He and fellow trainer Greg Jackson expected Rousey to be aggressive, perhaps to her own detriment. Jackson, in particular, reads people extremely well. Rousey, he felt, would get angry and push the pace, perhaps even charge right at Holm to try to establish a physical and psychological advantage. If that ended up being the case, the team intended Holm to be ready.

"We started off the camp with people just charging across the cage at Holly and Holly almost having to matador them," Winkeljohn says. "We had big guys just run at her and try to push her into the cage, so she got real quick at moving off at angles...Holly just about cried almost every day the first few weeks of camp and we were trying to frustrate her and make it difficult. But she was ready for everything Rousey tried."

As they prepared to walk to the cage, it occurred to Winkeljohn that they had been there before. He told Holm that what she should expect was a "Christy Martin moment," a chance to respond to an opponent losing control when faced with discomfort.

Rousey's facade began to slip early, when Holm avoided her every charge, defended smartly against the cage, and tucked her arms in tight and dropped her hips to avoid Rousey's favorite judo throws. By the time the first round was over, Rousey had almost completely lost her composure.

"Ronda does a lot of things very, very, very well," Winkeljohn says. "But she does those same things over and over again. We knew if we could mitigate her strengths and take her out of her comfort areas, she'd be somewhere she'd never been before in MMA—which is a war. And we'll come out ahead, but Holly has been in wars before."

Holm had an answer for everything Rousey threw her way. The opposite, it turns out wasn't true. It was, according to Vice's Jack Slack, a masterful performance:

"When she was matched with Ronda Rousey, most figured she was a lamb to the slaughter. But the flaws in Rousey's game matched up perfectly with the experience and discipline of Holm. Rousey moved in on straight lines and could not cut the ring, Holm could circle the cage beautifully and never took two steps backwards without breaking the line of attack. Rousey's head movement was non-existant and Holm's counter punches were laser accurate against such a static target. Rousey never, ever shot for takedowns or changed levels so every advance she made to the clinch was a run from distance through Holm's striking range. Rousey exhausted herself chasing Holm, then by eating punches."

The Martin moment came early in the second round. It's been GIF'ed a million times, to the point even casual fans can likely picture it, perhaps with the literal bull horns jokesters like to put on Rousey's head. Like Martin, Rousey charged recklessly forward. Like Martin, she missed her mark, completely and badly. Unlike Martin, her momentum sent her all the way to the mat—the ring ropes, at least, had saved the boxer that indignity. 

"She's fighting Ronda Rousey and she's like 'Oh s--t, it's Ronda Rousey.' She didn't say that, but you can tell what's going on in a fighter's mind," says Winkeljohn, who was in the corner that night. "Everybody acts tough, but that's a moment that could give anyone pause.

"When the Christy Martin moment happened, Holly jumped to a different level. All of the sudden she went into attack mode. Everything she did was hurting Ronda. I was most proud of the left straight she dropped her with right before the knockout. When she pushed her away to set up the kick, I was pretty sure it was about to be over. That's a technique we practiced a lot."

Rousey was women MMA's breakout star, becoming a cultural phenomenon that transcended the sport. She was a mainstream commodity, as likely to be discussed on Good Morning America as she was on Sports Center. 

In the wake of her upset win, Holm shouldered that role and proved to be a winning antidote to Rousey's increasingly toxic presence. Thousands of people showed up for a parade in her honor in Albuquerque after her win, and a number of women and girls around the world took note of a new role model they could be proud of. 

"Ronda Rousey versus Holly was the biggest fight of all time to me. I've seen Holly become an inspiration for so many people in so many ways," Winkeljohn says. "She's brought the moms who don't mind their daughters wanting to grow up to be like Holly. She's the opposite of the other side of the coin, where it's all about how much skin I can show, listen to me use bad language. Those types. 

"Look at the web traffic. Look at social media. You can almost add up all the other women in the UFC together and Holly equals them all. It's incredible."

It's true that Holm has almost double the social media following of her opponent on Saturday, bantamweight champion Amanda Nunes, the only other woman to beat Rousey in the Octagon. It's a testament, both to the power of Rousey's stardom at the time and Holm's iconic performance that night in Australia. 

"Obviously the numbers skyrocketed after the Ronda fight," former Bleacher Report MMA editor Brian Oswald says. "But even long after that, for fights like the one with Valentina Shevchenko on Fox, the web traffic wowed us. Holly was a legit needle-mover in her own right, even as she got further and further away from the Ronda fight."

Holm has actually lost four of her six fights since the Rousey upset. Most of her UFC fights, both before and after, have gone to decision, her careful footwork and tactical approach essentially designed to eliminate the kind of fireworks that made her famous.

"It's not a matter of making fans happy," Winkeljohn says. "It's a matter of getting no brain damage, getting the 'w' and going home and living your life."

Minus Rousey, Holm likely never headlines a single UFC event, let alone five of them. But beating her made Holm an immediate star and her Q-rating has endured both the years and a number of championship losses in the cage. It's why she was elevated into a title fight with Germaine de Randamie coming off a loss and why she's been selected to fight Nunes despite losing twice as many fights as she has won post-Rousey. 

Holly Holm's knockout win dropped a bomb on the world of women's MMA. It's only right that she ride the aftershocks for as long as they continue to reverberate. 

Jonathan Snowden covers combat sports for Bleacher Report.