A claim has been staked for the £105 million EuroMilliions jackpot won on Tuesday.
It is not known whether the UK ticket-holder is an individual or a syndicate.
National Lottery operator Camelot said the prize will be paid out at a ticket validation appointment before the winner decides whether to go public.
The big prize on the 25th anniversary of the first National Lottery draw was the sixth EuroMillions jackpot banked in the UK this year.
Andy Carter, senior winners’ adviser at the National Lottery, said: “What a way to celebrate 25 years of the National Lottery.
“This is the sixth massive EuroMillions jackpot win in 2019 and follows the nation’s biggest ever win of £170 million just last month.
“We now focus on supporting the ticket-holder as they start to enjoy their newfound wealth.
“There is another chance to win big tonight with a £25 million must-be-won Lotto jackpot up for grabs. Make sure you have a ticket to be in with a chance to win big.”
A UK ticket-holder won the £170 million EuroMillions jackpot in October, making them the UK’s biggest winner.
The previous biggest UK winners were Colin and Chris Weir, from Largs in North Ayrshire, who won £161 million in July 2011.
A £123 million jackpot was won by a UK ticket-holder in June and a UK winner scooped £38 million on the EuroMillions in April.
Ade Goodchild, from Hereford, bagged £71 million on March 15 and Patrick and Frances Connolly, from Northern Ireland, won £114.9 million on New Year’s Day.