Transit Divisional Response Unit members are investigating an assault at the Richmond Railway Station last week, Victoria Police say.
Around 8.45 pm on Saturday 1 December a 30 year-old man was using his mobile phone on platform 6 when an unknown man walked past him.
The unknown man then turned around and approached the victim from the side and punched him violently to the left side of his head.
The victim was rendered unconscious by the assault and collapsed to the ground, further striking his head and back.
The unknown man then fled down the stairs at the East end of the railway station.
There was no contact between either party prior to the assault.
The man received facial, back and head injuries and was transported to hospital by ambulance, he has since been released.
The offender is perceived to be Caucasian with a medium build, aged in his 30-40s and had a shaved head.
Investigators have released CCTV and images of a man they believe may be able to assist with their enquiries.
Anyone with information is urged to contact Crime Stoppers.
