A record £50.4m jackpot was not won in Wednesday’s National Lottery draw and will roll over to Saturday.
The new estimated jackpot of £57.8m must be won or shared out on Saturday, operator Camelot said.
Camelot the National Lottery organiser says it sold about 200 tickets per second in the hour before ticket sales closed at 19:30 GMT.
The previous largest jackpot was £42m, which was shared between three separate ticket holders in January 1996.
The National Lottery website crashed at about 18:00 on Wednesday, leaving people unable to purchase tickets for the draw for about 10 minutes.
Parts of the website – including the result page and sign in page – remain down with an error message saying they are “extremely busy”
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.
This reduced the odds of a player getting six numbers from about one in 14 million to one in 45 million, mathematicians say, but Camelot argues its rule changes have increased the chances of becoming a millionaire.
New Camelot rules mean the jackpot prize is shared out in the first draw after the prize reaches £50m.
This means if no player matches all six numbers on Saturday the prize will be shared between winners in the next tier where there is at least one winner – most likely those who have 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”.