A man ended up in hospital after he was attacked by a stranger in a street in Doncaster.
The 20-year-old told South Yorkshire Police he was repeatedly punched in his face by a man who approached him near to Danum Road, Bennethorpe, last Thursday morning.
The attacker was around 6ft tall, of a stocky build and was wearing a light grey fishing hat.
A 26-year-old man arrested on suspicion of assault and has been bailed pending further inquiries.
A South Yorkshire Police spokeswoman said: "The victim was allegedly punched several times in the face before the unknown man ran from the scene.
"The 20-year-old suffered serious facial injuries that required hospital treatment.
"Were you in the area that morning? Did you see the assault?"
Witnesses or anyone with information about the attack should call South Yorkshire Police on 101 or Crimestoppers, anonymously, on 0800 555111.