Superman punch: Anthony 'Showtime' Pettis stuns Stephen 'Wonderboy' Thompson with one-punch KO

Former UFC lightweight world champion Anthony 'Showtime' Pettis delivered one of the most spectacular knockouts of 2019 so far with a stunning off-the-fence 'Superman Punch' knockout of Stephen 'Wonderboy' Thompson in Nashville.

Former WEC and UFC lightweight world champion Pettis moved up to welterweight to take on two-time UFC 170lb title challenger Thompson in a battle of two of the very best strikers in the UFC.

And, despite finding himself on the wrong end of things for much of the opening two rounds, Pettis spied the opportunity to unleash something spectacular - and it paid off.

Backed up against the fence for the first time in the bout, Pettis then planted his foot against the cage, pushed forward and launched himself through the air into a flying 'Superman Punch' that connected clean on Thompson's chin, knocking him out instantly.

The technique was reminiscent of Pettis's legendary 'Showtime Kick' from his 2010 WEC fight against Benson Henderson as he jumped off the fence to land a kick on his opponent's jaw and send him to the canvas.

It was the first stoppage defeat of Thompson's career, and announced Pettis as a major factor in not one, but two weight classes as he campaigned for fights against opponents in both divisions moving forward.

Pettis' stunning KO win drew praise from his fellow UFC fighters, with welterweight contender Ben Askren exclaiming: "SHOWTIME!!!! Yeah baby."

UFC lightweight contender Dustin Poirier reflected on the sudden nature of the finish, tweeting: "1 mistake is all it takes in there."

And UFC bantamweight contender Aljamain Sterling reacted by tweeting: "I can't believe that just happened. I know Pettis is a beast in the stand up department, but I felt Wonderboy's size and striking would win it. This fight game is crazy."

Fellow lightweight-turned-welterweight Kevin Lee offered his congratulations and responded to Pettis' callout, saying: "@Showtimepettis that was sick. Beautiful to watch. Killed his legs. Congrats. I got my hands on RDS May 18 already."

And longtime UFC middleweight Brad Tavares noted how moving up to welterweight seems to have galvanized a few lightweights in recent months.

He tweeted: "Crazy how many 70ers are actually 55ers. not to mention they making waves. Last 2 cards, Masvidal and Pettis both former (possibly still current) 55ers."