Broadmeadows police are hoping to identify two men following an assault at Coolaroo in May.
The incident occurred outside a dessert store on Somerton Road about 7pm on Wednesday, 20 May.
Investigators have been told a man was shopping inside the store when he became involved in a verbal disagreement with an unknown man.
The 35-year-old man left the store and walked to a nearby car park when he was approached by the same man and a second unknown man.
The first man stopped the victim before the second man head butted him to the face.
Both men then took off and fled on foot.
The Thomastown man sustained serious facial injuries during the incident and was transported by ambulance to hospital.
Police have released images of two men who they believe can assist with their enquiries.
The first man is perceived to be 25-35 years-old, with a medium build and dark hair.
He was wearing grey hooded jumper, black track suit pants and black runners at the time.
The second man is perceived to be 22-30- years-old, with a small build and black hair.
He was wearing a fluro yellow jumper and grey pants with white paint on them.
Anyone who recognises the men or who witnessed the incident is urged to contact Crime Stoppers on 1800 333 000 or file a confidential report at www.crimestoppersvic.com.au.