Man assaulted in Rotherham park – did you see what happened?

Detectives investigating an incident in which an 18-year-old man was assaulted in a park in the Maltby area of Rotherham are asking witnesses to come forward. 
Between 1.30-2am on Saturday 28 October, the man was walking his dog through Coronation Gardens Park, just off Tickhill Road, when he was approached by two men, both described as being in their early 20s. 
One of the men is then said to have assaulted the man, striking him in the face causing him to fall to the floor and rendering him unconscious. The man was left with serious facial injuries which required hospital treatment. 
Due to the nature of the assault, officers have limited descriptions of the offenders; however one is described as wearing a yellow hi-vis jacket. 
Officers want to hear from anyone who saw or heard anything suspicious in the area at around that time. 
If you can help please call 101 or Crimestoppers anonymously on 0800 555111 quoting incident number 179 of 28 October 2017.