Punters and bookies alike are gearing up for the Grand National, one the biggest horse races in the world taking place on Saturday, with bookmakers estimating some £500 million ($731 million) will be wagered in the U.K. on the day.
The annual race, hosted at Aintree race course in North West England, is the single biggest sporting event of the year for bookies, with bets likely to exceed 10,000 a minute an hour before the horses set off.
The Grand National festival takes place over three days, but a huge bulk of bets of the £500 million will go on the main race, with the main prize of £1 million topping any other prize money offered for a "chase" race, where horses run over fences, outside of Japan, according to Aintree Racecourse.
"It is the calm before the storm right now. Some 90 percent of all bets on the big race come on the day of the race, where we expect 600,000 individual bets or 10,000 bets a minute to come in online in the hour before the race," a spokesperson for bookmaker Paddy Power told CNBC.
"It is the most stressful time of the year for our servers, not just for us but across the entire industry," he added.
Big favorite for the race is "Shutthefrontdoor", who will be ridden by famous jockey Tony McCoy in what will be his last ever Grand National before he retires later this year.
McCoy is thought to have ridden 4,000 winners over jumps during his illustrious career. If he takes top prize in this year's big race it will not be good news for bookies.
"It is likely that it will be the worst ever result for bookies if he wins. Crazy amounts of money being put on him at the moment. A win could put the industry in the red by £50 million which affects the bottom line. Last year's World Cup doesn't even come close," a spokesperson for Paddy Power said.