Pettis stuns Thompson with Superman-punch KO

Pettis on potential fight vs. McGregor: 'Let's do it' (0:59)

Anthony Pettis reacts to his knockout win over Stephen Thompson and provides his thoughts on a potential fight against Conor McGregor. (0:59)

Former lightweight champion Anthony Pettis made a superhero splash in his welterweight debut Saturday, knocking out two-time title challenger Stephen "Wonderboy" Thompson with a Superman counterpunch with 5 seconds left in the second round of the main event of UFC Fight Night at Bridgestone Arena in Nashville, Tennessee.

Pettis, who in addition to once reigning at 155 pounds and fighting at 145, became just the third fighter to win in those UFC weight classes and 170 pounds, joining Kenny Florian and Conor McGregor.

Pettis (22-8), who came in having lost five of his eight bouts since dropping his lightweight belt in 2015, was getting lit up for much of this striking battle, with Thompson's crisp jabs turning his face into a bloody mess.

"He was catching me with his jab, and I knew he had the range on me," Pettis said. "I was trying to beat him up with low kicks. I knew I was hurting his back leg, and that's what set up the right hand."

Thompson (14-4-1), a former karate and kickboxing specialist who now has won just one of his past five fights, had been using fluid movement to keep the fight at his preferred distance for the better part of two rounds.

But then, just seconds before the Round 2 horn was to sound, he ploddingly closed the distance and paid the price. Pettis, whose background is in taekwondo, sprung away from the cage and knocked out Thompson with one big right hand. It marked the the first knockout loss of Thompson's career.

"I was piecing him up with the jab, I was trying to break his arms with the roundhouse kick, man. And with the sidekicks, I guess I didn't turn my hip over enough, and he just drilled me with a right hand," Thompson said in a live video on his Facebook page after the fight. "After 80 fights, I've never been KO'd. This is the first time, and from a small guy, like a 155'er.

"I can't believe he got me with the Superman [punch]."

Afterward, Pettis was in no rush to decide what weight he would fight at next.

"I don't want to fight no one behind me, especially at lightweight," he said. "That's why I was like, 'Let's move up. The results show.' The weight cut was killing me at 145, 155. Now [at] 170, I'd better be in the top 10, bro."

Pettis said he would like a rematch with the man who took his lightweight title from him, Rafael Dos Anjos, who now competes as a welterweight. But then Pettis came up with an even better idea for UFC president Dana White, pointing to a top-10 lightweight fight taking place next Saturday.

"If Dana wants to give it to me, the winner of [Edson] Barboza and [Justin] Gaethje. I'm ready," he said.