A video captured the moment a strapping straphanger aboard a Los Angeles Expo train turned into a real-life Hulk and knocked out an unruly, shirtless man with a swift chokehold.

In the two-minute video posted to YouTube, the shirtless man can be seen harassing passengers on the train in a threatening manner on Saturday night.

Suddenly, a commuter identified as Adrian Kaczmarek — who goes by the nickname “Viking Guy,” according to The Daily Mail — shows up and quickly puts the disorderly passenger in a chokehold.

Kaczmarek kept the man subdued and locked in the chokehold for close to 15 seconds before briefly knocking him unconscious to the floor of the train, the viral video shows.

“I was more concerned about my safety and the people on the train safety. I wasn’t sure if he had a knife or if he had a gun,” Kaczmarek told NBC Los Angeles.

Kaczmarek put his foot on top of the man’s chest as the flailing man pleaded for him to “stop,” the video shows.

“I finally saw it escalating to the point where he was getting physical and people are getting pushed around. The whole thing is about to explode. I thought the best thing to do was go over there and subdue him,” Kaczmarek said.

The problem passenger was arrested on suspicion of being under the influence of a controlled substance, NBC Los Angeles reported.

The video, which was posted to YouTube over the weekend, has gained more than 1.2 million views.

“That guys foot was like Thor’s hammer. Can’t be moved,” YouTube User Dustin Cleveland commented.