As the calibre of horses at the Grand National has improved the race has become "less of a lottery", according to Racing Post's Lee Mottershead.
However, "there are very, very few [horses] you can say 'that has no chance of winning'".
The biggest betting day for UK horse racing has arrived as the world's most famous steeplechase race is set to take place at Aintree Racecourse.
Forty runners and riders will be participating in the four-mile, four-furlong (7.2km) course.
Last year's winner Many Clouds will lining up once again in a bid winning the race back-to-back emulating the feat of legendary Red Rum who won in 1973 and 1974.
Twice winning jockey Ruby Walsh will miss the showpiece after fracturing his wrist on Friday, trainer Willie Mullins said.
In a change from tradition, the famous race will start an hour later than usual at 17:15 BST.
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Last year's winner Many Clouds heads a maximum field for the Crabbie's Grand National at Aintree on SaturdayRead the full story ›
A man is being questioned by police over an alleged assault after a video emerged online of an Aintree racegoer appearing to deliberately knock an elderly man to the ground.
Officers investigating the video, believed to have been taken outside the racecourse said the victim had suffered injuries to his face and they were now speaking to a man who had come forward.
We are aware of the Aintree YouTube video and enquiries are currently being made. Thank you for your concerns
The incident was captured on a mobile phone by a friend of the suited racegoer.
In the video, onlookers can be heard gasping in shock and seen rushing to the man's aid before calling for an ambulance.
A Merseyside Police spokesman said: "The incident is being treated as assault and officers are speaking to several people believed to have further information that could help the investigation."
Many Clouds has won the Grand National at Aintree for trainer Oliver Sherwood and last year's winning jockey Leighton Aspell.
Successful aboard Pineau De Re 12 months ago, Aspell was never too far off the pace and Many Clouds, winner of the Hennessy Gold Cup at Newbury earlier in the season and sixth in the Cheltenham Gold Cup, jumped with aplomb throughout.
For a long way it appeared Shutthefrontdoor could provide Tony McCoy with a fairytale second National triumph before his retirement, but he eventually weakened into fifth place.
Many Clouds tired from the elbow, but had enough in the tank to hold off Saint Are, with Monbeg Dude third and Alvarado fourth.
Many Clouds has won the Grand National at Aintree.
The Winners Bar at Aintree has been renamed in jockey AP McCoy's honour ahead of this afternoon's race.
McCoy, who will be riding favourite Shutthefrontdoor, has said he will retire if he wins on a record 20th appearance in the race.
Liverpool manager Brendan Rodgers sounds like a man who knows his way around a racehorse. If you fancy him as a tipster for the Grand National, he's all over Portrait King.
Brian O'Connell will replace the injured Robbie McNamara aboard Lord Windermere in the Grand National at Aintree on Saturday.
The jockey steps in for the ride aboard the 2014 Cheltenham Gold Cup winner after McNamara sustained chest, abdominal and spinal injuries from a fall at Wexford on Friday.
O'Connell has previously ridden Tharawaat to finish eighth and last year was on board Quito De La Roque, who pulled up at the 21st fence.