Police are appealing for witnesses for an unprovoked attack on Saturday (July 7) in Worthing town centre.
The victim was walking on Montague Street at about 3am when a man approached him outside Topman and Topshop.
The 22-year-old victim was punched in the face and was left with a black eye and a broken nose.
He was taken to hospital to be treated for his injuries.
The suspect is described as white, in his early 20s, 5ft 5in with short dark hair. He was wearing jeans and a pale t-shirt.
PC Sara Coulson said: “This was a nasty unprovoked attack and we want information to bring this man to justice. The victim doesn’t know his attacker but anyone who witnessed this assault should get in touch with police on 101 quoting serial number 0296 07/07 or call the independent charity Crimestoppers on 0800 555 111.”