The UK's biggest ever Lotto jackpot is sending ticket sales soaring ahead of an estimated £50.4 million up for grabs tomorrow - and the promise that it must be either won or shared out on Saturday.
National Lottery operator Camelot said it expects to sell 200 tickets a second during the hour before tomorrow's draw.
The huge pot has eclipsed the previous highest jackpot of £42 million shared by three winners in 1996.
The biggest cheque won on a single Lotto ticket was £22.5 million shared by work colleagues Mark Gardiner and Paul Maddison from Hastings in 1995, and the biggest ever individual Lotto winner is Iris Jeffrey from Belfast who won £20.1 million in 2004.
Wednesday's jackpot is the result of 13 consecutive rollovers and follows the number of balls in the draw increasing from 49 to 59 in October, reducing the odds on a player's six numbers coming up from around one in 14 million to one in 45 million.
Camelot has claimed the "enhancements" actually give a better chance of winning and better odds of becoming a millionaire but the move has not been popular with all players.
However if no-one wins the jackpot on Wednesday or Saturday, Camelot will enact new regulations which stipulate that it must be shared out.
The rules say that the jackpot has to be won in the first draw after it reaches £50 million, meaning that if no players match all six numbers the prize will be shared between winners in the next tier where there is at least one winner, most likely those who have just five main numbers and the bonus ball.
Camelot said this would make it "some of the best odds players have ever had to win a multi-million pound life changing jackpot".
A National Lottery spokeswoman said: "The National Lottery is all about millionaire making and Wednesday's jackpot has the potential to make one of the biggest in our history.
"Don't delay getting your ticket as giant jackpots and millionaire making on this scale mean it is going to be one of our most popular draws ever. And remember each and every ticket sold helps raise more money for National Lottery Good Causes."
But Dr John Haigh, emeritus reader in mathematics at the University of Sussex, warned players not to get too excited.
The odds of winning the jackpot on Saturday by getting six numbers or five and the bonus ball would be around one in 6.5 million, he said.
"People get excited by looking at the sum of money involved. But that excitement is somewhat dampened when you look at the odds involved.
"I've never bought a ticket and I'm not going to break my record now."