Lottery players have just days to claim a £58m Euromillions jackpot.
The £58m winning ticket was bought in the South Ayrshire area of Scotland on 17 March, but there has been no payout so far.
Someone has until 13 September to make a successful claim or the money will be redistributed to charities.
A claim was made on the prize in April, but Camelot said that claim has not yet been validated. The group refused to provide further details, saying it does not comment on the validation of individual claims.
The winning numbers were 5, 7, 8, 16, 20, with the lucky stars 2 and 12.
The 180-day claim deadline for another £1m Euromillions win, which should have been won by someone who bought the ticket in Leeds, expires on 16 September.
That was a UK Millionaire Maker prize, bought for the draw on 20 March, with winning numbers MGKX92653.
The highest jackpot to go unclaimed was £63.8m, which should have been paid out after a ticket was bought in Stevenage and Hitchin in 2012.
It comes as the jackpot for Saturday’s draw is now a guaranteed £20m, which may trickle down to increase the size of smaller prizes if the jackpot is not won again.
Camelot’s Andy Carter, senior winners’ adviser at The National Lottery, said: “The next Lotto draw will see an amazing £20m special ‘Must Be Won’ jackpot up for grabs.
“A ‘Must Be Won’ draw means there could be lots more winners winning lots more if the jackpot rolls down.”
Saturday will be among the first of a series of special lottery draws taking place in the coming months, with millions more pounds up for grabs.
In November, players will be given a chance of winning an extra fiver by matching two numbers.