The young man, believed to be in his twenties, was found bloodied and unconscious following an alleged attack by a group of up to eight Asian men outside Capital Square on Campbell Street, Haymarket at 4am.
It is understood the victim stopped breathing twice and had to be resuscitated at the scene by paramedics.
According to one eyewitness, who alerted police to the incident, the violent attack was sparked when the man approached the group asking for cigarettes or money.
"One of the guys threw a cigarette in his face. I went to the traffic lights and then I looked back and he was on the ground, with four of the blokes around him, " Mr Ammar, a taxi driver, said.
"I saw the last kick (to the man assaulted)".