Before he became a superstar, Conor McGregor made quick work of Marcus Brimage in Stockholm in his April 6, 2013 debut. He then called for a $60,000 bonus from Dana White. (1:05)

The Ericsson Globe arena in Stockholm was empty, save for a few fighters shadow boxing and getting a feel for the Octagon in the middle of the floor.

Suddenly, one of the fighters scaled a side of the cage and straddled it, feigning a celebration, raising No. 1 with both hands and saluting an imaginary crowd.

The fighter wore sweatpants and a T-shirt with an image of himself draped in an Irish flag.

Conor McGregor wasn't just preparing for his first fight in the UFC on April 6, 2013. He was envisioning a takeover.

"He understood that moment was not going to be bigger than him, and he knew he was a superstar in that moment," said Lex McMahon, the manager of Marcus Brimage, McGregor's first UFC opponent. "He was just waiting for the world to understand."

"UFC jitters," as McGregor called them, would not be part of his indoctrination. He labeled himself the "mental champ," and part of that was not letting distractions, even a painful wisdom tooth that should have been surgically removed, get in the way.

Watch: McGregor vs. Brimage on ESPN+ Watch Conor McGregor take on Marcus Brimage in his UFC debut on April 6, 2013. It's the fourth preliminary bout on the undercard of the Gegard Mousasi vs. Ilir Latifi main event.

Watch the complete card on ESPN+

"Makes no difference whatsoever, it's just another contest," McGregor said earlier that week. "UFC, PFC, OFC, makes no difference what it is.

"I don't feel any different. It's you vs. you. You compete against yourself to become better."

McGregor built a 12-2 MMA record before making his UFC debut on the undercard of the Gegard Mousasi vs. Ilir Latifi main event. The Fight Night card was on Fuel TV, and McGregor vs. Brimage was the fourth preliminary bout.

It was the beginning of a historic career for McGregor, one that has featured dramatic highs and lows. That roller-coaster ride began several months before he first entered the Octagon, as he struggled with doubt about his future.

ESPN interviewed several people who were on hand for the beginning of McGregor's UFC journey. McGregor's quotes were collected from reporter scrums and a video blog McGregor's longtime coach, John Kavanagh, produced around the event. The interviews painted a picture of a 24-year-old athlete who was evolving from not knowing if he should continue in MMA to predicting he would take over the sport.

Editor's note: Answers were edited for length and clarity.

It was his UFC debut, but Conor McGregor made surgical work of Marcus Brimage, finishing him in 67 seconds to earn the knockout-of-the-night bonus of $60,000. Josh Hedges/Zuffa LLC/Zuffa LLC via Getty Images

Kavanagh, McGregor's longtime coach and owner of Straight Blast Gym in Dublin: Conor had kind of drifted away from the gym because he just didn't seem to be getting anywhere. It wasn't long after he won the second world title with Cage Warriors [on Dec. 31, 2012], so he had two belts, and I think he was fighting for between $500 and $1,000. So you're doing that three times a year. You're getting enough money to pay for your training. He was saying, "Well, I guess I better try something else." I had been harassing [UFC matchmaker] Sean Shelby, and eventually he replied late January -- I still have that email. He said, "Look, there's a fight April 6."

I was in Iceland and very excited, and I started ringing Conor and he wouldn't answer. I heard he wasn't showing up in the gym to teach his class. He thought I was ringing him to give him a hard time about that. Eventually, I had to text him and say, "Answer your bloody phone. The UFC has been in touch." So he picked up the phone, and you know how Conor is, very calm and calculated, doesn't get hyper or excited? I could almost hear him screaming all the way to Iceland without needing a phone.

UFC president Dana White first heard of McGregor at a Dublin pub on Feb. 12, 2013, after receiving an award earlier that day at Trinity College.

White: The place was packed, full of people. I was in there with the fans all night, and everybody kept talking about Conor McGregor. Sean had heard of him, so we flew him into [Las] Vegas and he and I went to dinner, and I was blown away by him. When I got in my car, I called [then-UFC owner] Lorenzo [Fertitta] and I said, "Let me tell you what, I don't know if this kid can fight, but if he can even throw a punch, this kid is going to be a huge superstar."

The fight was set, but during McGregor's training camp, Kavanagh urged him to address a problem that kept getting worse.

Kavanagh: For weeks in the gym, I'd say, "Conor, please go see a dentist." "Yeah, yeah, yeah." Next week, same problem. "Conor, go see the dentist." "Oh yeah, yeah, yeah."

McGregor: Sunday [March 31], I wake up and my wisdom tooth is coming through. Horrible pain. Crippling pain. Couldn't sleep, five days before the weigh-in. So I had to ring a doctor to come out to the house. He gave me antibiotics. But I told him I had a fight coming up, so he gave me baby antibiotics, didn't do jack s---.

play 3:36 Kavanagh remembers McGregor's first UFC fight SBG Ireland head coach John Kavanagh tells the story of Conor McGregor's first UFC fight, shortly after McGregor won his second world title in Cage Warriors.

It was time to fly to Sweden, but McGregor had to make a stop on the way to the airport.

Kavanagh: Dee [Devlin, McGregor's fiancée] drove me and him to the airport. We had to stop off to collect social welfare on the way. He'd take pictures with people and chat with people, and I'm like, "We're going to miss this flight for your UFC debut." And I don't have money to pay for another flight. Conor doesn't have money to pay for another flight.

McGregor: Then I fly over to Sweden, the fight's in four days, and the pain is still there. No sleeping, waking up at 6 o'clock in the morning in a bad way, can't open or close your mouth.

Kavanagh: So on Wednesday we went to the dentist and they said, "You're going to need an operation to take this out." I was like, "OK, if he gets an operation today, can he compete Saturday night?" They were like, "No, of course not. He's going to be under anesthetic." I said, "This is a disaster." Then the dentist came up with a plan. He said, "I'm going to clean as best I can, get a lot of salty water in there and get the infection down," because he couldn't take antibiotics [because of drug testing for fights]. He couldn't take anything for a fever. He couldn't take any of that stuff.

McGregor: These are just challenges. You just have to improvise and overcome these things. That was just another thing I had to overcome. Nothing was going to stop me.

An hour before weigh-ins on April 5, McGregor was sitting by himself in the stands of Ericsson Globe, looking at the huge video board hanging from the ceiling. There was a highlight video that would be played later during fighter introductions. McGregor smiled when his highlights were displayed.

McGregor: I feel good. It's done now. The hard work is done.

McGregor felt he and his fans were getting in the head of Brimage, and he made sure to keep the pressure on during the ceremonial square-off after the weigh-ins. Josh Hedges/Getty Images

McGregor weighed in at 145 pounds for the featherweight fight. Brimage, wearing a Dragon Ball Z Scouter, which resembled half of a plastic eye shield, also weighed in at 145. As Brimage stepped off the scale for the ceremonial square-off, McGregor already was in his stance, appearing ready to fight. McGregor put his fists on each side of Brimage's head. Brimage kept his hands down and stood there as McGregor talked trash inches from his face. McGregor put his forehead against his opponent's and Brimage pushed him away. McGregor knew Brimage had been upset by the taunting of McGregor's Irish fans, and he sensed his opponent becoming distracted. The head games became a part of McGregor's skill set as he developed into one of the biggest trash talkers in UFC history.

McGregor: I just said, "Listen, you're nearly 30 years old now [Brimage turned 28 on fight day], I think it's time to stop wearing the superhero mask." I don't think he heard it. But it should make no difference at all. In interviews, he said the Irish people -- my supporters -- were hounding his Facebook page, hounding his Twitter. Things like that don't bother me. They shouldn't bother any fighter. Say what you want, but it's not going to make a difference when I get in there. It's emotion free, and I think he was emotionally attached to the contest.

John Morgan, USA Today reporter: We were in Sweden, and I remember not being sure if his popularity in Ireland would translate. We'd all heard stories about how Ireland was behind him and had bombarded Dana White, trying to get him in the UFC, but we weren't sure if it would translate. I remember at the weigh-ins, hearing the chants, "There's only one ... Conor McGregor." I was like, dude, it's his debut and he's got people from Ireland traveling over. It was a little peek into how the Irish fan base could be.

Every combat specialist dreams of their 1st @ufc WEIGH IN. I'm ticking off so many dreams as the days go by DREAM BIG pic.twitter.com/f8TXk7e0rj — Conor McGregor (@TheNotoriousMMA) April 5, 2013

Brad Pickett, ex-UFC bantamweight who earned a split decision over Mike Easton on the main card: I remember seeing [McGregor] in the lobby, thinking he has a lot of goals, and how he has to back this up, how he was conducting himself. I trained with Marcus Brimage [at American Top Team], and I knew Marcus Brimage was pretty tough. I thought [McGregor] was taking this a bit too lightly.

Burt Watson, former UFC event coordinator: He didn't have the strut, but he had a swag. He wasn't loud and boisterous, but he was outspoken. So, with those things I could see, "You know what, this kid wins a couple of fights and messes around and beats up some of the name guys that are around, he could be something." The more fights he won, the bigger personality he became.

McMahon, Brimage's manager: I got the opportunity to meet Conor and kind of sit down and talk to his team. I just remember you could tell Conor was a transcendent talent all week. You get in the elevator and, oh wait, you're with the opposing guy's team. That actually happened. I was in the elevator with Conor and his team, just by myself, and he was super humble, super good dude. But you could just tell he carried himself with this "I belong" mentality. Not cocky. I've never thought Conor was cocky, to be honest. He just knows what he can do.

Brimage wore a Dragon Ball Z Scouter to weigh-ins, and that gave McGregor a target for his trash talking. Josh Hedges/Getty Images

The fight lasted just 67 seconds. McGregor landed a series of uppercuts that knocked Brimage to his knees. McGregor climbed on his back and landed some shots before referee Bobby Lundel stopped the contest. Afterward, McGregor repeated his theory that Brimage had become too emotionally invested in the fight because of the taunting, and he had overthrown his punches, allowing McGregor -- who is a devastating counterpuncher -- to attack.

White: I'm blown away. It's his first fight ever in the UFC. He walked out and got in the Octagon like it was his 100th fight in the UFC. From the minute the bout started, he was nice and relaxed, moving around. Even after he gets the knockout, it's like he's been here before and done it 100 times. This kid is totally relaxed, he's a beast. I'm impressed.

Pickett: Marcus Brimage was not an easy scalp. I was really impressed with the way Conor McGregor dispatched him. It was clinical.

Kenny Florian, ex-UFC lightweight who was part of the broadcast team that night: Everything from the way he composed himself at the weigh-in, even though it looked like he was cutting a lot of weight, the way he was handling himself, we just felt he was ready. And in the fight, it not only showed what he could do with his striking, but that he could perform at a very high level, especially with all the hype around his first UFC fight.

play 2:06 Ariel and Chael relive McGregor's electrifying UFC debut Ariel Helwani and Chael Sonnen look back at Conor McGregor's UFC debut in 2013, which resulted in McGregor knocking out Marcus Brimage in Stockholm, Sweden.

During his postfight interview with Florian in the Octagon, despite there being several fights remaining on the card, McGregor put in his claim for the knockout-of-the-night bonus, which that night was $60,000. "Dana, 60 Gs, baby!" McGregor yelled. He would end up receiving that bonus.

Pickett: The bonuses back then were supposed to be $50,000, but we actually got $60,000. I got a bonus from that night as well, for fight of the night. The reason we got $60,000 was because after the weigh-ins Dana White gives you a little pep talk and he told us bonuses would be $50,000. Diego Brandao was on that card as well, and he said, "No, Dana. No, Dana. Make it 60 Gs." Dana said, "No, we can't, it's capped at 50." So Diego went off, and Dana said, "OK, 60 Gs."

McGregor (during the final news conference of the night): I just won $60,000. I'm just thinking about what I'm going to spend it on. I'm going to get a nice car. Maybe some suits, customized suits. Just last week I was collecting social welfare. I didn't have money before this. I was collecting 188 euros a week off social welfare. Now here I am with a 60-Gs bonus. I don't know what the f--- is going on.

Morgan: At the press conference, the first couple questions went to him. He was wearing a suit. You see more people these days wearing a suit, but back then it was more T-shirts. He gets the performance bonus, and you could see this big smile on his face as he realized, "Oh my God, this is the biggest paycheck I've ever made."

Pickett: We were in the press conference and straightaway I found him very, very charismatic, talking about how he was on the dole and now he has 60 Gs. I found him very, very funny.

Florian: I remember talking to him after the fight, asking, "What are you gonna do?" He said, "You know, I'm excited. My girlfriend just made some gluten-free pizza that I'm gonna eat. I can't wait to eat that. I've been cutting weight super clean." I thought that was cool. He was right back on it and very serious in how he was handling it. Most guys will celebrate with a regular pizza, at least, but there he was getting excited about a gluten-free break. You could tell how serious he was to get to the top.

My paleo pizza made with a chicken base, tell me that ain't the shit!! Some cheese on there 2 but hey, it's Sunday!! pic.twitter.com/gpPrZytG5q — Conor McGregor (@TheNotoriousMMA) April 7, 2013

McGregor: The whole week I felt like the star of this thing. I said I was going to steal the show. I feel like I stole the show, stole everything. I'm going to steal all the money from the UFC and hightail it back to Ireland with a big bag of money.

Contributing: Ariel Helwani, Brett Okamoto and Marc Raimondi