Police are appealing for information about the incident and trying to trace the driver of a black Audi A3 alleged to have been involved.
The victim said that at around 11.45am on Saturday 24th August the 18-year-old was travelling as a passenger in his partner’s car on Tanfield Way in Wickersley.
It is thought he asked her to stop the car while he got out to make a phone call.
It is then claimed that a black Audi A3 travelling along Tanfield Way in the opposite direction was unable to pass the other car on the road and began sounding its horn.
The Audi driver allegedly got out of the car, approached the 18-year-old who was still on the phone and punched him.
He was taken to hospital and treated for a possible fractured cheekbone and broken nose.
South Yorkshire Police officers are now trying to trace the Audi driver.
He is described as white, around 6ft tall, aged between 27 and 28-years-old, of medium build, with shaved light brown hair.
Anyone with any information should contact South Yorkshire Police quoting incident number 587 of 24th August 2013.
Alternatively call Crimestoppers anonymously on 0800 555 111.