THREE men are wanted over a sickening assault on an unsuspecting victim in a Collingwood lift.

A 56-year-old man was in an elevator at a Hoddle St apartment block, in Melbourne's northeast, about 7.50am on September 29 when he was attacked, police say.

Three men entered the lift on the morning of the AFL grand final and surrounded the victim. One of the men, dressed in a black hoodie and black pants, looked at his victim and smiled as the doors closed.

He looked in the direction of the security camera in the top corner of the lift before pulling his hands from his jumper pockets and unleashing a series of blows to the victim's head.

Police say the assault was unprovoked.

The offender is described as caucasian, approximately 30-years-old and 170cm tall. He has short dark hair and is unshaven. He was wearing blue Nike runners and a black Nike hoodie at the time of the assault.

Police on Monday released CCTV footage and images of the offender and two other men who entered the lift with him. All three are wanted by police for questioning.

A police spokeswoman told 3AW the attack was "disgusting, absolutely disgusting". The hosts said they were shocked by the vision and called the attacker a "dirtbag".

Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au.