PATERSON - A teenager pleaded guilty Wednesday to punching and knocking out a man for no reason on a street corner last year in a brutal "knockout attack."

Kristian Gonzalez, 18, of Paterson, faces three years in a juvenile lockup when he is sentenced next month, according to his attorney, Harley D. Breite.

Gonzalez was 17 when he approached a stranger last Dec. 7, 2015 and delivered a vicious punch as a 16-year-old friend recorded the crime. The video of the attack became viral and led to the arrests.

On the video, the other teen can be heard encouraging Gonzalez to strike the man. Both teens were charged with aggravated assault and endangering an injured victim.

The attack seriously injured Cesar Nejara, who said that he couldn't speak for a week after the attack and had to eat through a straw for eight days, Eyewitness News reported.

Breite said the plea deal calls for Gonzalez to serve no less than 85 percent of the three-year sentence.

Anthony G. Attrino may be reached at tattrino@njadvancemedia.com. Follow him on Twitter @TonyAttrino. Find NJ.com on Facebook.