A 26-year-old man suffered a fractured skull in a "senseless" unprovoked attack in Invercargill over the weekend.
Police said the local man was walking with two friends along Dee St, near the corner of Don St, when he was seriously assaulted about 3.20am on Saturday.
Acting Senior Sergeant Ben Butterfield said the attacker, who was unknown to the victim, punched the man once, causing him to fall heavily to the ground.
"The victim has suffered a skull fracture with bleeding on brain," he said.
The man was taken to Dunedin Hospital where he remains in a stable condition.