An Oldham supporter was stabbed after watching Sunday's FA Cup third-round tie against Liverpool at Anfield.
Merseyside Police said the 35-year-old man flagged down a passing ambulance in the vicinity of the stadium after a disturbance at about 17:00 GMT.
A Merseyside Police spokesman said the fan, whose injuries were not life-threatening, is refusing to talk to detectives.
Police have appealed to other fans and passing motorists for information.
Detective Chief Inspector Andy O'Connor said: "The area was very busy with both football fans and passing motorists when the incident took place and I'm confident some people will have seen what happened."