A jackpot prize of more than £22 million has still not been claimed, a National Lottery spokesman said.
Players are being urged to check their tickets by lottery operator Camelot after one lucky UK winner's numbers landed them the life-changing sum during Friday's EuroMillions draw.
The winning numbers were 5, 6, 11, 30, 44 and the Lucky Star numbers were 2 and 6.
A National Lottery spokesman said: "We have our player services team on stand-by waiting for the ticket-holder's call.
"They are experts in helping winners through the initial stages of their win so they can start to enjoy their new found wealth as quickly as possible.
"Our team will be on hand every step of the way to guide players through the winning experience."
The spokesman said the area where the ticket was bought will be released on March 15 if no one has come forward to claim the prize.
He said the ticket-holder has until 5.30pm on Sunday August 29 to claim the cash, but if no one comes forward, the money and all the interest it has generated will go to National Lottery Good Causes.
The winning ticket-holder should call the National Lottery Line on 0845 910 0000 to register a claim.
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