Perth man charged over one-punch assault

A man is in custody following a one-punch attack outside a bar in Perth that left another man unconscious.

The 21-year-old Nollamara man allegedly punched another man, 23, in the back of his head as he was walking through the courtyard of the Murray Street bar about 12.20am on Saturday.

The victim lost consciousness after hitting his head on a table and the brick pavement, and was taken to Royal Perth Hospital for treatment.

The younger man has been charged with grievous bodily harm and is due to face the Perth Magistrates Court on Saturday.