Police are appealing for cellphone footage of an alleged ''coward punch'' assault in an alcohol queue at the Six60 concert in Dunedin on Saturday night.
Senior Sergeant Craig Dinnissen, of Dunedin, said three people, all believed to be known to each other, were arrested after the incident.
The victim remained in hospital this morning after suffering serious injuries.
Police believe the incident was an unprovoked attack on the man in an alcohol queue at Forsyth Barr Stadium, and he was not known to his alleged assailant, Dinnissen said.
"The victim was knocked to the ground and repeatedly beaten by this offender.''
"A coward punch.''
Another man, aged 23, was arrested for fighting in a public place and possession of a Class-C controlled drug.
Dinnissen said a third man, 32, part of the "same crew'' was arrested for allegedly assaulting, obstructing and hindering police.
The man is alleged to have spat at officers during the incident.
Police appealed for witnesses of the assault to come forward.
"If anybody's got cellphone footage then please come and assist police in holding these people to account.''
About 40 people locked up in the cells of Dunedin Central police station at the weekend.