John Moyle was at a function at his local rugby club on Saturday night when he received a text asking if he could open his supermarket to check a Lotto ticket that might be worth $40 million.
The people needing the ticket checked were "a friend, of a friend, of a friend" of his wife Julie and the Fresh Choice Green Island owner didn't hesitate to get the ball rolling.
Moyle called his supervisor to meet him, Mrs Moyle and the ticket-holders at the supermarket.
He said the supervisor was "shaking" as she put the ticket barcode to the scanner; the machine beeped and the screen read $13.36 million.
Their prize was one of the three $13.36m shares of Lotto's record-breaking $40m Powerball.
He said the "bewildered" couple were "blown away" and hugged after the ticket was confirmed.
"We had a beer and a Champagne in store and started doing the paperwork and Lotto rang."
Being part of such a big win was "unbelievable", Moyle said.
"I was stoked, so I don't know how they coped ... I struggle to grasp having that amount of money go into your bank account and they were the same - they were over the moon, but were in disbelief."
The couple talked about spending the money on houses, cars and travel.
Moyle did not know the couple and did not ask them their names.
"I didn't want to know, we know their friends but we didn't know who they were ... that means I can't tell anybody, which suits me fine."
When he told people at the club the ticket had been bought by a Dunedin couple, everyone was pleased.
"Everyone is happy Dunedin got a big prize. Sure we all wanted it to be us, but the fact it was Dunedin was great."
The three winning tickets were sold at Pak 'nSave Dunedin, Oparau Roadhouse, in Te Awamutu, and on MyLotto to a player from Hamilton.
The numbers were: 29, 27, 37, 18, 33, 3; the bonus number was 36 and Powerball was 7.
The must-go biggest cash prize on offer was rolled down to the three Second Division winners after the First Division failed to be won.
Due to phenomenal draw sales, Strike Four also reached a Must Be Won draw. That jackpot was won by two lucky players in Auckland and Waipapa who both won Strike Four to take home $405,792 each.
A Lotto spokesman confirmed the Dunedin prize had been claimed.
Lotto chief executive Wayne Pickup said more than 2.7m tickets were bought for Saturday's draw.
"We've never seen this much demand placed on our business before.
"At our busiest time yesterday, between 5 and 6pm, we were selling over 3000 tickets a minute."
Lotto sales for the week were just under $60 million, with sales for the Must Be Won draw accounting for $40 million of that.
"I'd like to thank our retailers and staff, who all did an absolutely amazing job during the week.
"And I'd like to thank our players, who really got into the spirit of the game. I've never seen so many people happy to queue. I saw complete strangers chatting to one another, imagining what they would do if they won."
Pickup said MyLotto online was dealing with 10 times its normal traffic and accounted for around 15 per cent of total ticket sales.
"There have been reports of our website crashing after the draw, and with close to 100,000 people trying to check the results at the same time it's not surprising some people couldn't get through."
He said the biggest Lotto winner will be New Zealand community groups.
"Thanks to Lotto players, every year around $200 million is returned to the community, via the NZ Lottery Grants Board."
Sport NZ chief executive Peter Miskimmin said: "Lottery funding helps us to enrich the lives of Kiwis and to inspire our nation through sport. The funding is used to get more Kiwis, especially kids, into sport and helps us produce more New Zealand winners on the world stage."