A couple from Suffolk have claimed last week's massive £148.6 million EuroMillions jackpot, the National Lottery has said.
The windfall will make the pair the nation's second richest lottery winners.
But they are keeping their identity a secret until Tuesday when they are expected to go public and reveal their plans for the future.
The couple, from the town of Haverhill, were the only winners in Friday's draw and scooped a staggering £148,656,000.
The sum is just behind the £161 million landed by Colin and Chris Weir, from Largs in North Ayrshire, last July. A difference in the exchange rate means this week's jackpot was slightly lower.
A National Lottery spokesman said: "A couple from Haverhill, Suffolk, have won the UK's second biggest ever lottery prize.
"They were the only winners in Friday's EuroMillions draw and have banked an amazing £148,656,000."
Theirs is the seventh lucky ticket to have hit the jackpot in the UK this year.
To date, the National Lottery has created some 2,900 millionaires.
Friday's winning numbers were 50, 21, 17, 48 and 11, and the Lucky Star numbers were 09 and 10.