EuroMillions players have been advised to buy tickets early for Tuesday's £149 million draw in order to avoid disappointment.
A late surge for tickets before Friday's draw caused Camelot's website to slow down, meaning some people missed out on the chance to play.
The lottery operator expects another late rush to purchase tickets for Tuesday's draw and has urged players to buy them early.
A Camelot spokesperson said "If you want to buy tickets, don't leave it to just before the draw.
"We had a particularly high level of traffic on Friday night with a steady flow of people seeing how high the draw was.
"Nearly £150 million is an incredible amount, it's got people really excited, so our advice is don't leave it to the last minute".
On Friday, there were complaints from players "unable" to purchase tickets moments before the draw online and were instead shown a message announcing it was experiencing "high levels of traffic".
The website also struggled in January ahead of a £50.4m UK lottery jackpot.
If there is a UK winner tonight they will be the second largest winner of the EuroMillions draw, after Christine and Colin Weir from Scotland picked up £161.6m in 2011.