COCONUT CREEK, Fla. -- Colby Covington is shadow boxing, warming up for a private striking workout. He's with a coach, inside a room tucked next to an acai bowls cafe. Rock music is playing on Covington's smartphone, and he's wearing a shirt that reads "Stomp my flag, I'll stomp your ass."

It's 1:06 p.m. on a Monday in mid-November at the famed American Top Team training center. A few feet away, on the other side of a closed door, the other pro fighters at the gym -- including ESPN's No. 2 bantamweight, Marlon Moraes, No. 5 flyweight Jussier Formiga and PFL standout Kayla Harrison -- are wrapping up a group class. Covington can't see his teammates when they gather in the center of the mat or hear them when they all yell "ATT!" in unison to end the session. That's partly by design, as some fighters prefer private sessions before a big fight. But for Covington, the isolation is deeper.

"I'm doing stuff behind closed doors now," Covington says during lunch, a month before his first unified title shot. "I don't want people to see my training. That's a big concern of mine. I don't want people to see the game plan I'm working and how much I've improved and the skills I'm developing every single day. You'll see that on fight night when I step into the Octagon."

Aside from being one of the best fighters in the world, Covington is known for being one of the UFC's greatest villains. He is skilled at incendiary -- and sometimes crude -- trash talk.

And it's not just with opponents. Over the last few months, Covington's divisiveness has shaken the walls of American Top Team. He has publicly feuded with several teammates, including former friend -- and perhaps the hottest act in the UFC -- Jorge Masvidal. The Covington-Masvidal beef has defined the growing tension within the gym and put a spotlight on ATT that will grow more intense should the teammates eventually become opponents.

In the meantime, Covington will challenge Kamaru Usman for the UFC welterweight title in the main event of UFC 245 on Saturday in Las Vegas. In his corner will be coaches from a gym -- the only gym Covington has known as a pro -- where at least one of its stars wants him to lose.

"I don't feel comfortable," Covington says. "I feel like I always have to look over my shoulder. I have to watch my back. I don't know if people are gonna come up and try to attack me. I've had people yelling in the gym at me, creating scenes and stuff. It's not a good environment for me there."

But some argue it's an environment Covington helped create.

"Colby doesn't need to watch his back at our gym," says Dan Lambert, owner of American Top Team and Covington's agent. "He might need to watch his back just about anywhere else he goes as a result of what's happened. ... There's pros and cons to being who Colby is and that just might be one of the things he needs to deal with moving forward.

"I think Colby thrives on that chaos," Lambert continues. "['Chaos'] is his nickname and appropriately so. I think it pushes him to go harder at those people and at the gym."

How Covington went from afterthought to one of the sport's most polarizing figures dates back to June 17, 2017, when he beat Dong Hyun Kim. UFC matchmaker Sean Shelby told Lambert after that fight that the UFC had no interest in re-signing Covington when his contract was up after his next fight.

Lambert says he told Covington he shouldn't alter his fighting style, but "there's some other s--- you can change."

After decisioning former title challenger Demian Maia on Oct. 28, 2017, in Sao Paulo, Brazil, Covington called Brazil a "dump" and its fans "filthy animals" while standing in the Octagon.

Covington's new identity had come to life. And it was drawing attention. Covington's ATT teammate Amanda Nunes lashed out at him on social media. Another Brazilian fighter, former UFC heavyweight champion Fabricio Werdum, threw a boomerang at Covington a few weeks later during a fight week in Australia.

The strategy worked. The UFC re-signed Covington, and his next fight was for the interim welterweight title, which he won by beating Rafael dos Anjos at UFC 225 on June 9, 2018.

If not for the sudden turn, Covington says he would have been out of a job, "just another guy nobody cared about." Against Maia, he says he made $30,000. Against dos Anjos in his next fight, Covington says he took home $200,000.

"I'm trying to be a high-paid fighter," Covington says. "I'm not trying to fight for 20 grand the rest of my career, getting my brains knocked in, lose brain cells and not have something to show for it at the end of my career. You see a lot of these guys at the end of their career, they're brain dead, they have no money, they're doing GoFundMe accounts. It's sad, dude. After I'm done, I want to be set, man. I don't want to have to work another job."

After seeing early returns, Covington accelerated his transformation.

Mixed martial arts is an individual sport, but in gyms and training centers all over the world, athletes and coaches work as teams to help fighters prepare and evolve. Many fighters say they wouldn't be where they are without their teammates, sparring partners and coaches.

Covington upset many with his comments in Brazil, but turning against Masvidal fractured the gym.

"You never talk bad about your teammates, doesn't matter if you like them or not," former UFC strawweight champion and ATT veteran Joanna Jedrzejczyk said.

It's one thing to be controversial, but to some fighters at American Top Team, Covington sold his soul for headlines.

Not long ago, Covington and Masvidal were more than teammates. They were friends and roommates.

Covington says the beef started after he beat Maia, because Masvidal lost to Maia earlier that year. Covington says Masvidal became jealous.

Masvidal says the falling-out started when Covington stiffed one of their mutual coaches, Paulino Hernandez, on a payment for working the dos Anjos fight.

But hard feelings were kept private. Masvidal worked Covington's corner when he faced dos Anjos and celebrated his teammate's win. Covington would later say that although Masvidal worked the corner, he didn't help Covington make weight and, in fact, abandoned him.

But when Masvidal knocked out Ben Askren in a UFC-record five seconds on July 6, Covington posted on Instagram about always having each other's backs.

Both would later say the relationship had soured by then. The fracture started becoming more public in late July, when rumors circulated that Masvidal could fight for Usman's crown ahead of Covington, who was quoted on July 30 saying it would be crazy if Masvidal landed a title shot despite being 2-2 in his last four fights.

Masvidal and Covington had words in the audience at UFC 241 on Aug. 17 and security stepped in at the Honda Center in Anaheim, California.

The feud boiled over two days later on Ariel Helwani's MMA Show, after Covington joked that Masvidal was trying to improve his seating by getting closer to Covington in the first row. Masvidal said Covington told UFC president Dana White that Masvidal was going to assault him -- and that White then warned Masvidal about getting into a confrontation.

Masvidal grew agitated during his interview with Helwani and referred to "some stuff" between Covington and one of the coaches, likely the payment issue. Masvidal said Covington knew what gym he's at and when he's there, and he said he could be there the following day.

Within the next few weeks, Masvidal and Covington had a verbal altercation at American Top Team.

"I said, 'If you don't pay him, I'm going to F you up,'" Masvidal said on The Dan Le Batard Show. "My coach got in between it."

Lambert says he sat down for a meeting with Masvidal after that altercation, and Masvidal agreed not to come to blows with Covington inside the gym out of respect for the team. Masvidal has called ATT home for 15 years.

"They're gonna act like professionals," Lambert says. "They're gonna coexist. They're gonna do what the coaches tell them to do. Or they're not gonna be there. ... I don't think you'll see problems inside the gym, because they respect it."

Masvidal told ESPN he wasn't interested in talking more about a subject that could further divide American Top Team. Both Covington and Masvidal said they would never leave the gym, even if they sign to fight each other.

"We're better than that," Masvidal says of his teammates. "Maybe some shady s--- has gone down. But we're not slimeballs. I'm ATT until the day I die."

Covington and Masvidal are both welterweights, ranked No. 2 and 3, respectively, by ESPN. The possibility of them fighting is real, and it's something Covington wants.

"You never talk bad about your teammates, doesn't matter if you like them or not."

Joanna Jedrzejczyk

"It's a big opportunity businesswise for both of us -- and for the gym," Covington says. "The type of hype around that fight? Honestly, that would probably be one of the most sought-after pay-per-views in the history of the UFC."

If Masvidal and Covington do end up booked to fight each other, Lambert says protocols would be put in place at the gym to ensure the best possible environment for both.

"It's not my favorite situation to be in, but I guess at the end of the day it's probably a good problem to have," Lambert says. "It means the gym is doing something right.

"We'll deal with it. We'll keep them separated. They'll train at different times. They'll train in different parts of the gym. They'll train with different training partners and different coaches. They'll both get the best possible training, they'll come in ready and it'll go one way or the other."

If the byproduct of a successful gym is occasionally having two fighters face each other, the downside of a beef like the one between Covington and Masvidal is the atmosphere it would create.

"It's just gonna be like Team Colby and Team Masvidal," Harrison said. "It's gonna literally divide the gym and divide the coaches. Nobody wants that."

But a potential matchup is further away than some think, according to Masvidal's manager, Abe Kawa. Masvidal has mentioned Conor McGregor or Nick Diaz as potential next opponents because they could produce bigger paydays.

"As of right now, he's not in our plans," Kawa says of Covington. "We're so far ahead of that. Usman and Colby are fighting for the right to possibly face Jorge. Jorge is the ticket -- he's the A-side."

On Saturday night, Covington could be considered the A-side for the main event of a card that features three championship fights. That's a long way from worrying about getting released by the UFC.

And while ATT teammates Masvidal, Jedrzejczyk and Dustin Poirier dislike Covington -- Jedrzejczyk said she hopes Usman will "beat his ass" -- there are those who understand his motivation, and even respect it.

"He's accomplished more in a short period of time than a lot of guys that have been in the industry forever," says Thiago Alves, a UFC veteran out of Brazil, a team leader and fighter-coach. "You can't hate the recipe. You don't have to like it, but you have to respect it. I respect the dude and I like him. ... I'm ATT, man. Forever. And he's a great kid. Never disrespected me. Yeah, say some s--- to sell it. But even with everyone here, he's always been super respectful."

Nunes was one of the first to criticize Covington on social media after his "filthy animals" comment about Brazilians. Now they share a head coach, Conan Silveira, and Nunes says she harbors no ill will toward Covington.

Silveira, also a Brazilian, says he has not taken any of Covington's remarks personally and understands what Covington's goals are by talking trash. He says hard feelings within an MMA gym are not rare, but they shouldn't be a problem as long as everyone stays professional about it.

"Do you get along with everyone in your family?" Silveira asked. "Colby at American Top Team is a completely different guy. He's a part of the family. ... Of course I'm gonna support him. It's never that I'm gonna turn my back on him. I say that on behalf of me and them. We're never gonna do that."

Covington believes those who knew him before what pro wrestling fans would call a "heel turn" should see that he is just trying to maximize his income in a cold, dangerous sport.

"It shows me their true colors and it shows me who they really are inside," Covington says. "They can't understand I'm doing this because of business? They've seen me for the last eight years at the gym. And they know who I really am deep down inside. But when a camera turns on, when a mic is put in front of my mouth, it's a different story, because I'm doing business at that point. And that's how I look at it."

Not everyone differentiates between the trash talk of a showman and real bad blood.

"All these words, they do have consequences," Masvidal told Le Batard. Askren, a noted trash-talker himself, found out the hard way. After knocking out Askren, Masvidal added a couple extra shots and later called them "super necessary."

Covington embraces the challenge.

"[There's] a unique element to it where I do actually enjoy and thrive in people wanting to see me get knocked out, people wanting to see me lose and fail," Covington says. "There's something really nice that I like about it that makes me want to just prove them all wrong and shut them all up."