The National Lottery website has crashed before tonight's record EuroMillions draw worth £169million.
Users have been unable to use the website and there have also been problems using the app.
Tickets for Tuesday night's draw must be purchased by 7.30pm.
Online website users are shown a screenshot of an apology when they try to play, claiming that the site is up and running but a "bit busy".
The biggest jackpot ever is up for grabs and players will only need five balls and one lucky star - as opposed to two - to increase their chances of winning compared to last week.
And it comes after a senior Lottery boss revealed that today's draw "must be won".
If no one manages to get all tonight's numbers, the money will roll down into lower tier prizes - meaning there could be several multi-million pound prizes on offer instead of one big win.
Lottery boss Andy Carter said: "This means, if the jackpot isn't won on Tuesday, it will roll down into the next prize tier where there is at least one winner."
