A man had his jaw fractured and teeth knocked out in a vicious assault in Melbourne's inner north, police say.

The 23-year-old victim was walking down Gertrude Street, Fitzroy, with his partner when he was attacked by an unknown man about 11.20pm on Monday August 11.

Police wish to speak to this couple in relation to the bashing.

He was taken to hospital and required surgery for his injuries, a police spokeswoman said.

Investigators believe the attack may be linked to an earlier run-in between the victim, another man and a woman outside a pub at the corner of Gertrude and Brunswick streets.