Lotto NZ head of communications Marie Winfield said the other winner yet to claim their prize bought their ticket from Collingwood Foodcentre in Invercargill.
Winfield said they expect to hear from the winners soon.
"Either they know they have won and are laying low for a while to let the gravity of their life-changing windfall sink in, or they are completely oblivious and have a very big surprise in store for them," Winfield said.
Onekawa resident Janice Donnelly, who bought her ticket from Andrew Spence Pharmacy, said she believed the unknown winner was being deliberately quiet.
"God, I would have claimed it right away," she said. "I need the money."
Fellow resident Lynn Gibson said all eyes have been on Facebook, waiting to see if someone owns up.
"I get Lotto about twice a week and have won three figures a few times," she said. "But this is a whole new level."
Another hopeful punter queuing at the store added: "If it was me, I wouldn't be here buying another one."
Onekawa councillor Richard McGrath confirmed that he purchased his ticket from Andrew Spence Pharmacy, but said he wouldn't be resigning to sit on a new fortune.
"Well done to the winner," he said.
"I advise them to take a deep breath and seek financial advice prior to spending their new fortune.
"And well done to the pharmacy too, as they are a lovely team that work there - always polite and friendly."
McGrath said this time around, rumours about who the winner is haven't really circulated in the Napier suburb.
Winners can claim their prize in-store or call the Lotto New Zealand team.
