"My brother went online and double checked that I had the right draw, then read the winning numbers back to me as I carefully checked them off on my ticket. When I told him I had all six he got so excited and said: 'I'm pretty sure you've just won Lotto!'"
His brother suggested he return to the supermarket to claim the prize the next morning when the store would be quieter, with the man then tucking the winning ticket sitting safely in his wallet.
He returned to the store the next day to claim his $1m prize.
With his new-found fortune, the winner is looking forward to paying off his mortgage and taking a few more holidays.
"I'll definitely take my brother out for a drink when I see him next – we've definitely got to celebrate!"
The winning ticket was sold at Greymouth New World for last Wednesday's draw.