Melbourne Embona detectives are appealing for witnesses following a robbery in Flagstaff Gardens on 16 November.
Investigators have been told two men approached the victim in the park, struck him in the head and stole his mobile phone about 2.25am.
The 18-year-old North Melbourne man received minor injuries and was treated at the scene.
Police have released images of two men they believe can assist them with their enquiries.
The first man is perceived to be Pacific islander in appearance and wearing maroon, blue and white jacket, black pants with a white stripe and a black beanie.
The second man is perceived to be Pacific islander in appearance and wearing a blue hooded jacket with a green clover symbol on the back, black pants and black shoes.
Anyone with information or who witnessed the incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au