The 19-year-old victim was approached and assaulted by another man following a brief argument in Lichfield.
He was left with serious facial injuries, including a broken jaw, after the incident on Market Place, near The Scales, at around 11.50pm on August 5.
Staffordshire Police have released CCTV images of the suspect, who is white, in his early 20s, around 5ft 8ins tall, of slim build and with dark short hair. He was wearing a green and white camouflage pattern jacket.
Anyone with any information should contact the force on Facebook or Twitter, quoting incident number 197 of August 7 or call 101.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org