You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Someone is $20.2 million richer than they were yesterday after a Big Wednesday first division win last night -- but they might not even know it yet.
No one has come forward to claim the prize, Lotto New Zealand said.
The lucky punter will go down in Lotto's history books -- winning the fourth largest prize won by an individual ticket.
Lotto NZ spokeswoman Kirsten Robinson said most people came forward within a few days if they had won a big prize.
"Some smaller prizes go unclaimed for longer [and] sometimes people have sat on it for a few days."
A Christchurch winner of $22 million last year took four weeks to come forward, she said.
"It's always exciting to find the winners."
The winning ticket was sold at Countdown Pukekohe South in Auckland.
The ticket holder won $20,048,756 with Big Wednesday first division and $197,319 with Big Wednesday second division.
This is the third time this year that the Big Wednesday jackpot has been struck.
In February, a Kaikoura couple took home $8.5 million and in April a winner in Takaka won $7 million.
Lotto is encouraging anyone who bought their Big Wednesday ticket from Countdown Pukekohe South to check it immediately at any Lotto outlet or online.
Largest Big Wednesday prizes:
June 2009: $36,890,256 (Kuripuni Lotto and Post Shop, Masterton)
Sept 2009: $27,004,410 (AJ's Lotto, Tauranga)
Sept 2013: $22,569,174 (Pak'N Save Riccarton, Christchurch)
Sept 2014: $20,246,075 (Countdown Pukekohe South, Auckland)