Grand National 2015: Punters set for famous horse race
Thousands of people are descending on Aintree Racecourse for the annual Grand National spectacular - which could prove to be a tricky day for the bookies.
Champion jockey AP McCoy's horse Shutthefrontdoor is expected to be the best-backed horse in recent Aintree history.
Bookies are predicting £150m will be spent betting on the event.
They claim they could lose some £50m if McCoy were to win.
David Williams of Ladbrokes said: "A McCoy win is our nightmare scenario."
He added: "Shutthefrontdoor could easily be the best-backed horse we've ever known in the Grand National. We're scared even to think about it.
"More often than not Aintree throws up a host of stories but this year there's only one show in town. The entire race revolves around one man and one horse."
The annual race, now its 168th year, is famed for its unpredictable nature, with 39 horses competing at 16.15 BST.
Thousands of spectators are once again heading to the Merseyside racecourse, following the success of Friday's traditional Ladies Day event.
But the race has not been without controversy and this year supporters of national campaign group Animal Aid led a protest against it.
Campaigners scaled the fourth plinth in London's Trafalgar Square to wrap Gift Horse, by Hans Haacke, in a banner that reads: "Horse Racing: You bet, they die."
They aim to draw attention to the dangers faced by racehorses, claiming 40 horses have died at the three-day Grand National meeting since 2000.