The incident happened just before 3 a.m. Tuesday morning near West 44th Street and 9th Avenue in Hell's Kitchen.
According to police, the man they're looking for was riding a moped at the time of the attack.
Video shows suspect driving onto the sidewalk and bumping into a 56-year-old man. The pair exchanged words before the victim pushed the man on the moped. That's when the suspect punched the man in the face twice, knocking him unconscious.
A 38-year-old man, a friend of the first victim, jumped out of a livery car to confront the suspect and was also knocked out after being punched in the face. He was taken to Bellevue Hospital in critical condition.
The older man was taken to Mount Sinai and is recovering.
Meanwhile, the suspect was able to get away on the moped following the incident.
ALSO READ | Councilwoman accused of biting NYPD officer at Brooklyn homeless shelter protest
Councilwoman arrested during protest against shelter in Brooklyn
----------
* Get Eyewitness News Delivered
* More New York City news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube