Police are hunting three men over what they describe as a cowardly "king hit" attack which left one victim in hospital with a significant head injury and another with facial fractures overnight.
They have released security camera images showing a group of people on St Asaph St, between Colombo St and Durham St, where the attack allegedly took place at around 1am.
Police say the ordeal began with a fracas between the two victims and three men in their early twenties. It was broken up by security officers and friends of the victims, who are brothers.
An attacker then allegedly came back for more - king-hitting one of the victims - and both brothers were injured in fight that followed.
Police are looking for witnesses to the attack and say one of the alleged attackers was a ginger or brown-haired Caucasian of stocky build and between 172cm and 180cm in height. He was wearing a light-coloured button-down long-sleeve shirt with dark pants and shoes.
The other two alleged attackers are described as MÄori, one of stocky build and the other thin build, wearing dark clothing. Police also want to find a silver Subaru Legacy seen in the area.
Information can be left directly with Detective Senior Sergeant Leairne Dow at Christchurch Central Police Station on (03) 363 7400 or anonymously through Crimestoppers on 0800 555 111.