A Lotto Rollover jackpot prize of £6m is waiting to be claimed from a ticket bought in Rhondda Cynon Taf.
The mystery ticket matched all six numbers in the draw on Saturday 29th June. The search is now on to find the owner of the winning ticket.
A National Lottery spokesperson said: “We’re desperate to find this mystery jackpot ticket-holder and unite them with their winnings – this amazing prize could really make a huge difference to somebody’s life.
"We’re urging everyone who bought a ticket in this area to check their old tickets again or look anywhere a missing ticket could be hiding."
If the ticket holder doesn't come forward, the prize money will be donated to The National Lottery Good Causes.
The winning numbers were 7, 13, 25, 31, 34, 45 and the bonus ball was 4.
Anyone who believes they have the winning ticket should call the National Lottery Line on 0845 910 0000.