Man fights for life after one punch attack

A man is being questioned by detectives after a one-punch attack in Sydney's east left a young man with critical injuries.

In an unprovoked attack police have labelled disgusting, a 21-year-old man was standing on a footpath along Bondi's beachfront early on Sunday when he was hit from behind.

Police say the man had an argument with another person outside the Oporto chicken and burger store on Campbell Parade before he was punched.

The victim, believed to be from the NSW south coast, fell to the ground and hit his head on the concrete.

His attacker kicked him as he lay on the ground before fleeing.

The victim was rushed to St Vincent's Hospital in a critical condition where he remained on Sunday.

Just after midday on Sunday, a 32-year-old man went to Waverley Police Station.

He is assisting police with their inquiries but no charges have been laid.

Acting Superintendent Chris Stiles said the victim had been at a soccer game during the afternoon before heading to Bondi.

"All local police and members of the community would be disgusted by the attack," he told media.

In another violent attack in Bondi on Sunday morning, a man in his late 20s was hit over the head and robbed just before 3am.

Police say the man was walking home on Roscoe Street when he was hit over the head with a blunt object.

His attacker made off with his mobile phone and wallet.

The victim received stitches for his head injury.

Sunday's one punch attack occurred on the same strip where 24-year-old Michael McEwen was hit unconscious and stomped on in December.

Mr McEwen spent eight days in a medically-induced coma and had part of his skull removed after he fell backwards during the assault and hit his head on the footpath.

McEwen's attacker, David Hona, was sentenced last week to a minimum of four years and nine months behind bars.