Counties Manukau Police said they were investigating a serious assault outside a bar on Queen Street in Ōtāhuhu late last night.
Around 11:30pm a 52-year-old man was attacked by a small group of people unknown to him during an argument.
During the attack he was struck over the head with a wine glass, Acting Detective Sergeant Warwick Worth said.
The man remained in Middlemore Hospital in a critical but stable condition after emergency surgery, he said.
“We are following strong lines of inquiry, but if there is anyone who knows who is involved or saw what happened, we’d like to hear from you.”
Information can be passed to Counties Manukau Crime Squad on (09) 261 1321, or to Crimestoppers, anonymously if necessary, on 0800 555 111.