Gearoid Walsh, 23, was punched to the ground in the same area of the beachside suburb as Irishman David Keohane was viciously attacked in August last year.

Police said Mr Walsh arrived in Australia on a working visa just a month ago.

He had been out drinking with his brother on Sunday when he got into argument with a man outside a takeaway food shop on Arden Street about 11pm.

Mr Walsh walked away but returned to continue the argument and the man punched him, police said.

Mr Walsh stumbled and fell, hitting his head on the ground.

He was not breathing and was in cardiac arrest by the time police arrived.

He was taken to Prince of Wales Hospital with severe head injuries and was on life support all week.

Police today said he died in hospital overnight.

Mr Walsh's mother arrived in Sydney on Wednesday. His sister lives in Randwick and his brother lives in Brisbane, police said.

Police have not been able to find his attacker, despite capturing his image on CCTV footage.

The man was described as being of white or European appearance, aged between about 25 and 30 years, of average build, 175 centimetres tall, with a clean-shaven, round face and short, brown and slightly curly hair.

He was wearing a white V-neck T-shirt and jeans.

Anyone with information should phone Crime Stoppers on 1800 333 000.

Mr Keohane, now 30, was a flooring contractor and Australian permanent resident when he was set upon near the intersection of Brook and Kidman streets last year.

He was walking home with takeaway pizza after a night out.

Mr Keohane suffered severe head and facial injuries. He spent the next seven months in an induced coma before waking in April this year.

Twenty-year-old Thomas Isaako has been committed for trial for the attempted murder of Mr Keohane.