Players of EuroMillions are being urged to check their tickets after the UK winner of a £123million jackpot has failed to claim their prize.
Last Tuesday's £123,458,008 prize was scooped by one single ticket.
The winning numbers were 25, 27, 39, 42 and 46, with Lucky Stars 11 and 12.
Camelot said the ticketholder might be unaware they have won and is urging players to "check, double-check and triple check" their tickets.
The winning ticket matched all of the seven numbers.
Camelot could only reveal at this stage that the ticket was bought at a retailer, rather than online.
Andy Carter, senior winners' adviser at the National Lottery, said: "A week has slipped by and winners may have been going about their everyday routine completely unaware of this amazing change of fortune.
"The ticket was bought in-store so players should check the places they usually keep their tickets and make sure they've checked them all.
"We have the champagne on ice and our fingers crossed that the lucky winner comes forward to claim their win soon."
However, the area where the ticket was bought will be revealed in about a week's time if no valid claim has been lodged by then.