Police were called at around 6.40pm on Saturday, January 15 after the incident on Holme Lane, Hillsborough, was reported.
An area close to the Sports Shack bar and a takeaway was cordoned off by officers as they investigated.
One witness who passed the scene reported seeing part of the pavement closed off and three police cars in attendance.
A South Yorkshire Police statement said: “It is reported that two men ended up in altercation, in which one of the men punched the other, knocking him unconscious before leaving the scene.
“The victim was transported to hospital and found to have minor injuries.
“Officers have carried out enquiries to locate those involved and are now appealing for information.”
Anyone with information is asked to call 101 quoting incident number 700 of December 15.