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From the moment Holly Holm announced her intention to retire from boxing in 2013 to concentrate on mixed martial arts, she was put under the microscope, dissected and analyzed. At the time, she was already 31 years old. A veteran of 38 professional boxing matches, she had won championships in three weight classes and could rival anyone in the sport in competitive experience. She would come in the front door with the best hands in her division. Yet when it came to her overall potential, Holm was a mystery.

From the outset, however, she didn't hide her target: Ronda Rousey.

"A new challenge was a big part of it," Holm said during a press conference before her final boxing match. "She has opened doors for women in MMA. She's the one to beat and she's in my weight class, but I'm not ready to fight her tomorrow. I have MMA strengths but I need to build on my weaknesses."

With just two years of pure MMA training, her ascent to the top has been a quick one.

The nature of MMA is much more complex than it appears. You must gain proficiency in punching, kicking, maintaining or closing distance, clinching, wrestling, defending takedowns, working from the top, defending from the bottom and transition scrambling. Each of those core competencies has hundreds of known techniques and counters, and new ones are constantly innovated. In that way, the possibilities of attack and response are infinite.

That is the beauty of the sport, and it's also its curse. It is so multilayered that many a promising prospect has sunk under the inability to adapt. Because Holm had spent more than a decade in boxing, few knew how she would take to it. Would she implode, or was she the one who could beat Rousey?

In the history of MMA, no one who had ever won a major boxing championship had crossed over and won a title there.

That all changed on a warm Sunday morning in Melbourne, Australia, when Holm authored one of the most stunning and complete upsets in MMA history before a UFC-record crowd of 56,214. When the opening bell rang on the UFC 193 main event, BestFightOdds.com noted that Rousey was as high as a 16-1 favorite to impose her aggressive brand of combat on Holm and walk away with her seventh UFC title defense.

The belief was that it was simply too soon in Holm's mixed martial arts journey to fight Rousey—that she needed more mat time to prepare for Rousey's unrelenting, improvisational ground game that had mangled the arms of several opponents. The call even surprised Holm.

"I know a lot of people felt it was early," she said shortly after her win. "I didn't expect the phone call to come this early, but I always just look at it as, if you don't take the opportunities that are in front of you, how are you really going to expect to get somewhere? So as soon as it came, I said, 'Great, let's do it.'"

Holm came into the bout with two significant advantages. First, and most obvious, was her boxing. Rousey had made headlines just prior to the fight after landing the cover of boxing bible Ring Magazine, but insiders knew Holm was the technically superior of the two.

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The second and, as it turns out, equally important advantage was her coaching. In a beautiful case of serendipity, Holm was born and bred in Albuquerque, New Mexico, the base of arguably the most successful fight camp in MMA history, Team Jackson-Winkeljohn.

The latter of the two names, Mike Winkeljohn, discovered Holm at age 20 and had shepherded her career ever since. The former, Greg Jackson, is considered by many to be the top cage strategist, equal parts fighting savant and sage philosopher. Training alongside her on a daily basis were names like former UFC light heavyweight champ Jon Jones, former interim UFC welterweight champ Carlos Condit and current lightweight No. 1 contender Donald Cerrone, all of whom could impart real-time knowledge.

All along, the goal for Holm had been Rousey. So by the time she got the call, Jackson and Winkeljohn had scrutinized and deconstructed the seemingly unbeatable champion, catalogued her tendencies and developed concrete ideas to neutralize her strengths.

Their plan was manifold. First, Holm would frustrate Rousey's straightforward style with lateral movement, forcing her to chase. Then, when Rousey was overextended, the straight left would be there. High kicks would dissuade entries into the clinch. And if Rousey got to the clinch, one of her favored positions, Holm's coaches taught her several ways to counter Rousey's throws by emphasizing her hip levels and center of gravity. Finally, there was the decree to spend as little time tied up with her as possible. Space and distance would play in her favor.

Holm admitted after the fight that the preparation was so difficult that she cried several times throughout camp.

"Yes, there's moments in your mind that you doubt yourself, and you know things can happen and you can have a good night, you can have a bad night," she said in the post-fight press conference. "There's days in training where everything flows and days in training where they don't. You just pray that doesn't happen the night of the fight. So yeah, there's [tough] moments up and down the entire training camp. But those are the moments you need to dig deep."

Holm's execution of her strategy and defense was nothing short of stellar. She battered Rousey not only because of her hands, but also because her footwork was exponentially superior. Every time Rousey made the mistake of landing her inside foot inside of Holm's, thereby leaving herself open to Holm's power hand, she paid for it.

Holm did have to survive a few moments of trouble, notably during a ground scramble when Rousey only needed to free her own leg to lock in her famous armbar. Showing her attention to detail in preparation, Holm was a step ahead and escaped at the only available moment to do so.

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By the end of the first round, Rousey was in trouble, and Holm, who had been criticized in her first two UFC bouts for a conservative approach, turned up the heat. In a sense, Rousey was the perfect opponent at the perfect time, because her aggressiveness offered Holm a willing foil for her counterstriking. Much like Rousey had done to past opponents with her throws, Holm used her foe's momentum against her.

After hitting Rousey with straight lefts multiple times in the second round and then causing Rousey to miss wildly, Holm threw Rousey down and then floored her for good with a kick to the jaw.

Greg Jackson told Brett Okamato of ESPN.com after the bout:

It was pretty much what we thought would happen. Obviously, she's an amazing athlete and we have nothing but respect for her, but she's been very successful doing the same things for a long time, and we were able to capitalize on that. The other coaches and I got together, and we're not fans. We're not like, 'Oh God, Rousey is the greatest ever.' It's just a math problem to us. So it's hard to understand the perspective just because this is what we do for a living. This is my job to figure it out.

Holm, who had been bad-mouthed by Rousey on the eve of the bout—for no apparent reason—almost immediately knelt next to Rousey to check on her.

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According to those close to her, that concern for an opponent should come as no surprise. Nicknamed "The Preacher's Daughter" out of respect for her father, Roger, an Albuquerque minister, Holm has gained a reputation as role-model type. Still, most warn not to take that kindness for weakness.

Holly always had fight in her, Roger said, recalling in an interview with New Mexico news channel KOAT that even as a little girl, she would stand up to bullies.

"She just always had that courage about her," he said. "She never did like seeing people mistreat anybody."

Around her hometown, Holm is described as modest and kind, and the locals erupted with joy after her win. Her teammate, the former UFC champion Jon Jones, congratulated her by posting on Facebook: "Honestly can't think of anyone else who deserves to be a champion more than Holly Holm. Congratulations big sis!" The city of Albuquerque recently declared November "Holly Holm Month."

Around the fight world, her win served for some as a type of schadenfreude against Rousey, who had come to be viewed as overexposed and unnecessarily disrespectful—the latter is a characteristic that is not always penalized in a world that frequently prizes its antiheroes.

While Holm continued to exemplify class by defending Rousey against insolent critics, her stature has only grown. She walked away as the fresh-faced and dignified champion, the New Mexico cowgirl riding away with her white-brimmed hat after vanquishing the baddie. Whether she wants it or not, the spotlight is hers.

So far, the early returns are strong. According to Hookit, a platform that measures athletes' digital imprints, Holm has attracted over 1 million new social media followers since November 12.

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That number only figures to swell. According to the UFC, in the next few days, Holm has interviews scheduled with E!, Extra, The Talk, Late Night with Seth Meyers, the New York Times and Rolling Stone, among others.

All of this will likely set up a rematch with Rousey. It only took less than an hour from the time Holm landed the fight-finishing head kick for UFC President Dana White to admit he was leaning in that direction, saying, "I think the rematch is what people would want to see."

July 2016 is the likely target date, when UFC helps to christen Las Vegas' new multipurpose arena with UFC 200. For such a big event, what could be bigger than Holm-Rousey 2?

The historic underdog last time around is about even money to win the rematch, but opening lines are made to draw betting action. Realistically, it is Rousey who is the underdog, who has to adjust to losing for the first time, to suffering a blow to the ego and to realizing she isn't unbeatable. Holm has experienced all of that before. And more importantly, she has proved to be better.

As she moves along with more fame and more expectation, perhaps the best advice she can get was the advice she already gave herself, as she recounted to the media after her win.

"I think you can get so mentally beat by kind of working yourself up too much," she said. "So I just wanted to stay really level-headed. I believed in my training and my ability."

That was all she needed the first time, just a decade-plus to becoming an overnight champion.

Mike Chiappetta is a MMA senior columnist for Bleacher Report.