Justin Gaethje made a thunderous statement Saturday night at UFC Philadelphia.

The 30-year-old lightweight contender knocked out Edson Barboza with a highlight-reel punch at 2:30 of the opening round in UFC Philadelphia’s main event, which took place at the Wells Fargo Center and aired live on ESPN. A picture-perfect right hand is the shot that put Barboza down, giving Gaethje back-to-back first-round knockouts following his similarly dominant victory over James Vick last August. And for Gaethje, who moved back into title contention with the win, Saturday night was more than a little overwhelming.

“God, it’s such an unforgiving sport,” Gaethje said on the UFC Philadelphia post-fight show on ESPN+. “I mean, we work so hard. I’ve worked for 12 weeks, day-in and day-out, made so many sacrifices, and still the self-doubt just keeps trying to creep in, keeps trying to creep in. And I’m sure that happens to anybody with a hard job, or everybody in life it happens to, but you have to keep pushing through. And that’s all I do.

“Believe in my preparation, believe in the people I’ve surrounded myself with. This is crazy, man. I’m shaking. It’s really hard to control this right now.”

Gaethje’s performance against Barboza mirrored his performance against Vick in that the former WSOF champion entered UFC Philadelphia with a much more measured approach than his old brawling ways. Gaethje revealed afterward that the strategy was a conscious decision on his part, and one he’s been focused on perfecting since he lost his undefeated record with back-to-back KO/TKO setbacks against Eddie Alvarez and Dustin Poirier.

“After those two losses, I really was able to look in the mirror,” Gaethje said. “Before that I was undefeated and I really didn’t take the time to make the changes, because I didn’t know what was wrong. I was just having so much success. But now, my ability to slow things down is so amazing. I didn’t know I could do it. I didn’t know I possessed that skill. But yeah, it’s much more of an up-here (cerebral) experience for me, and I’m loving it. The last two fights have been so much different than my other two.”

Where Gaethje goes from here is anyone’s best guess.

The UFC’s lightweight division is a crowded and confusing place at the moment, especially at the top, with the trio of Tony Ferguson, Conor McGregor, and UFC champion Khabib Nurmagomedov all sidelined for the foreseeable future. Poirier and featherweight champion Max Holloway are slated to clash for an interim lightweight title on April 13 at UFC 236, and the only three other men currently ranked above Gaethje aside from Barboza — Al Iaquinta, Kevin Lee, and Donald Cerrone — all are already booked.

Ninth-ranked Paul Felder is the next-closest ranked lightweight to Gaethje on the UFC’s 155-pound roster, and he was coincidentally an anchor on the ESPN+ post-fight show. Felder respectfully threw his own name into the hat when Gaethje was asked about what was next — and Gaethje’s reply was blunt.

“You don’t want that to happen to you,” a smiling Gaethje told Felder.

Gaethje added that Nurmagomedov is the main target he is focused on, and vowed that he is willing to do whatever it takes to reach the undefeated Dagestani champion.

“When the time comes, it’s kill or be killed,” Gaethje said. “That means you or me. I don’t care who it is. It could be you (Felder), it could be Nate (Diaz), it could be Donald (Cerrone), it could be Khabib (Nurmagomedov). I don’t care. I’m on my way to Khabib and I want to fight him. I think I’m the toughest matchup for him.”