A UK ticket holder has claimed the £77,798,898.10 jackpot they won in Friday's EuroMillions draw, the National Lottery said.
Two players shared the £155 million jackpot, with the second winning ticket bought in Spain.
There were also seven £1 million winners in the UK in the special event draw - and all players are urged to check their tickets to see if they are a winner.
The jackpot prize will be paid out at the ticket validation appointment, which can only take place when the banks are open.
It will then be up to the ticket holder to decide whether they want to go public with their win.
Andy Carter, senior winners' adviser at The National Lottery, said: "Wow, what a win for one lucky UK ticket-holder.
"This is the 10th biggest winner this country has ever seen and we look forward to toasting their win."
"By buying a ticket for EuroMillions or any other National Lottery game, every player is helping to raise money for good causes."