LAS VEGAS — For the past four years, Justin Gaethje bided his time, gradually honing his skills while unleashing utter fury outside the mainstream of mixed martial arts. And on Friday, the former World Series of Fighting lightweight champion finally unveiled the division’s best-kept secret to UFC fans across the world.

In one of the most memorable Octagon debuts in recent UFC history, Gaethje put on the type of performance that has become his trademark, defeating Michael Johnson via second-round TKO in an instant frontrunner for ‘Fight of the Year’ at The Ultimate Fighter 25 Finale.

Gaethje (18-0) was long thought to be one of the best 155-pounders in the world outside of the UFC, and with his sensational performance over Johnson — who was ranked No. 5 on the UFC’s official lightweight rankings — the 28-year-old Arizona native proved that his hype was justified. The win vaulted Gaethje into instant UFC contention, and afterward, when asked what he’d like to see next, Gaethje indicated that he wasn’t looking to take things slow now that he had finally arrived on the world’s biggest stage.

“Whoever gets me closer to an interim title right now,” Gaethje said at Friday’s post-fight press conference. “(Conor) McGregor’s not here, so I’m going to get that interim title on my waist, then when he comes back: pressure. I pressure people. You think you can take it. He has a fantastic left hand. If he touches me with it, I’ll go to sleep. If not, you saw what will happen tonight. [Johnson] has never been finished (by knockout) before. I finished him in the second round.

“I got the biggest heart. I’m the most violent guy in this division. I’ll prove it time and time again. Every time, I’ve been ‘Fight of the Year.’ For now (this is it). I’ll fight again, that will be considered ‘Fight of the Year.’ I can take the most boring fighter and put him in that fight right there, so that’s what I do. I’m an entertainer.”

The build-up to Gaethje and Johnson’s clash was a memorable one which featured plenty of trash talk from both sides, however Johnson dialed things up last month when he brought Gaethje’s family into the equation. Gaethje said Johnson’s comments were still in the back of his mind during the fight — a wild contest that featured innumerable back-and-forth swings of momentum as Johnson had Gaethje badly hurt in round one, only for Gaethje to rally back with a stunning series of knockdowns in the second frame.

Gaethje then finished the job with a brutal salvo of strikes, blowing the roof off the T-Mobile Arena with a stoppage win at 4:48 of the second round to hand Johnson his first-ever loss via KO/TKO.

“I knew the leg kicks were going to add up,” Gaethje said, grinning. “He’s going to have a hard time sleeping comfortably for a couple nights, for a couple weeks. I’m there to break people. I said I would drop him and I would let him up, and that’s what I did.

“I broke him. I said I was going to break him, and I broke him.”

After the fight, Gaethje said he had one name on his mind. With lightweight champion Conor McGregor busy preparing to box Floyd Mayweather on Aug. 26, Gaethje set his sights squarely on the division’s current No. 1 contender: Tony Ferguson, a winner of nine straight whose only career UFC loss came against Johnson in 2012.

“That’s what I want,” Gaethje said. “Michael Johnson whooped his ass, so I will break him. Guaranteed. Call me a liar all you want.”

Coming into Friday night, many observers wondered whether Gaethje’s ultra-aggressive, constant-forward-pressure style would translate successfully into the upper echelon of the lightweight division. And while he proved that it could do so, Gaethje also acknowledged the same self-aware sentiment he has throughout his career.

“I’m not infallible,” Gaethje said. “Never will be. I will lose, like I said. I’m not scared to get knocked out, I’m not scared to lose. I’m scared not to perform.

“It sounds dirty, but I’m a promoter’s wet dream. What else can you ask for? I literally go in there and put it on the line. I have no regrets. I’m not scared to lose. I’m an entertainer. That’s proven, because I got a performance (bonus) and knockout of the night. That’s what I’m in there for. I’m here to make money, make a living. This is my job now. I was so ready for this. Everyone says ‘Octagon jitters.’ That’s because they’re not ready. There’s no reason to rush this process. If you’re a young fighter out there, take your time. Wait until you’re ready. I was so comfortable in back. I was so comfortable this whole week.”

Gaethje reiterated that McGregor is his ultimate goal, and that he would be more than happy to dethrone the lightweight kingpin in McGregor’s home country of Ireland if the opportunity arose. He also was aware that his UFC debut made an impression on “The Notorious,” who took time out of his boxing preparation to tweet out rare words of praise for his lightweight division-mate.

“It’s been pointed out to me that [McGregor] tweeted tonight about my fight,” Gaethje said. “Real recognize real. That dude’s a warrior, I’m a warrior. If I get the interim belt around my waist — I’ve only got to do that maybe one or two more times, and then, like I said, I’m not going to ask for the money fight; I’m going to be the money fight. You sound like a little b*tch when you ask for the money fight.

“I’m going to earn it, one at a time. I don’t care who’s next. I want to fight Ferguson, but he’ll probably say I’m not worthy. He lost to Michael Johnson. I just finished him. So he’ll be full of sh*t when he says that.”