Rachael Blackmore's mount Ain't That A Shame is among the favourites for Saturday's Grand National at Aintree.
The horse was backed from 20-1 to 8-1 on Friday for the trailblazing rider to win the race for a second time.
It would be a poignant victory for Irish trainer Henry de Bromhead, whose 13-year-old son Jack died in a riding accident seven months ago.
Last year's victor Noble Yeats, runner-up Any Second Now and third-placed Delta Work will all line up again.
A maximum field of 40 will contest the 175th running of the famous race at 17:15 BST.
There has been one equine fatality at the 2023 meeting and organisers will be hoping all runners and riders return safely.
Police say they will deal "robustly" with any disruption after animal rights activists threatened to sabotage the race by forming a human barricade across the course.
Bookmakers expect more than £150m to be wagered on the National, which takes place over 30 fences and four and a quarter miles.
After downpours on Friday, a largely sunny day is forecast, with the going described as soft.
Approximate odds: 8-1 Ain't That A Shame, 9-1 Corach Rambler, 10-1 Delta Work, Noble Yeats, 12-1 Mr Incredible, Gaillard Du Mesnil, 14-1 Any Second Now, Le Milos, The Big Dog, 16-1 Vanillier, 18-1 Longhouse Poet, 20-1 Capodanno, Galvin, Our Power, 25-1 Bar.
Runners in the Grand National face 30 fences over four and a quarter milesWho are the leading contenders?
Blackmore made history with Minella Times for De Bromhead in 2021 when becoming the first female jockey to win the Grand National.
"Everyone who is down at the start is in with a chance, that is the kind of race it is. It is really exciting to be part of it and on such a good horse - I can't wait," said the 33-year-old rider.
De Bromhead also saddles Gabbys Cross this time - with 27 of the 40 runners trained in Ireland.
Delta Work is one of six contenders for Gordon Elliott, who also has Galvin, Fury Road, Coko Beach, Escaria Ten and Dunboyne as he seeks a record-equalling fourth victory.
Davy Russell, who has temporarily come out of retirement after Elliott's stable jockey Jack Kennedy broke his leg, could be having his last ride aboard Galvin.
Sam Waley-Cohen triumphed in his final race a year ago on the Emmet Mullins-trained Noble Yeats, who is now partnered by Sean Bowen.
Emmet's uncle Willie Mullins, recovering at home after a hip replacement, runs Capodanno, Carefully Selected, Gaillard Du Mesnil, Mr Incredible and Recite A Prayer.
Fellow Irish trainer Jessica Harrington has been having chemotherapy for breast cancer and is hoping for victory with Lifetime Ambition.
She will watch the race at home and is staying positive despite saying there have been a "few bad days" and "tears" since being diagnosed in October.
"Being able to get up this morning and look at the scenery and horses - I am very, very lucky," she said.
Lucinda Russell - successful with One For Arthur in 2017 - trains Corach Rambler, winner of the Ultima Chase for a second year running at Cheltenham last month and bidding to become only the third Scottish-trained victor of the National.
The horse is owned by a syndicate of seven which includes 21-year-old student Cameron Sword, while jockey Derek Fox is set to return from injury for the race, just as he did when triumphant six years ago.
"Winning is a dream and if it happened it would be the best day of all our lives, but it is a 40-runner race and there is a lot that needs to go your way," said Sword.
Our Power, Eva's Oskar and Francky Du Berlais will seek to become only the second Welsh-trained victor, after Kirkland in 1905.
The Coral Trophy winner Our Power's part-owner Dai Walters has only just returned home from hospital where he has been since last November after a helicopter crash which also involved trainer Sam Thomas.
Le Milos heads the English challenge, with Harry Skelton riding for trainer brother Dan - they are sons of Olympic equestrian gold medallist Nick Skelton.
Last year's first two, Noble Yeats and Any Second Now, run again at AintreeGrand National in a nutshell
How long does it last? The winner usually completes the course in about nine minutes. The 30 jumps include Becher's Brook and The Chair.
What does the winner get? The total prize fund is £1m, with the winning team collecting more than £500,000.
Why are there different weights? It is a handicap steeplechase with runners allocated weights according to their ratings.
How old are the horses? The race is open to horses aged seven and upwards who meet specific criteria.
How many Grand Nationals have there been? This is the 175th running of the race.
What about safety? Significant changes were introduced before the 2013 race which saw the core of fences softened, the distance reduced and new procedures for loose horses. Two horses died in the race last year - there have been four equine fatalities from a total of 356 runners in the past nine editions.
Pundits' predictions
Gina Bryce, BBC Radio 5 Live presenter
1 Mr Incredible 2 Delta Work 3 Longhouse Poet 4 Any Second Now
It's win or bust for quirky character Mr Incredible but Patrick Mullins, who has overseen much of his individual training, looks to have him ready after an eye-catching run at Cheltenham.
John Hunt, BBC Radio 5 Live commentator
1 Longhouse Poet 2 Galvin 3 Le Milos 4 The Big Dog
Longhouse Poet has a great chance if ridden with more restraint than last year where his exuberance was his undoing. A patient ride will see him go close.
Andrew Thornton, BBC Radio 5 Live analyst and former jockey
1 Delta Work 2 Longhouse Poet 3 Capodanno 4 Ain't That A Shame
Third in the race last year, Delta Work had a great prep by taking the Cross Country Chase at Cheltenham, which Tiger Roll twice landed before his Grand National victories.
Gary O'Brien, Racing TV and BBC Radio 5 Live pundit
1 Capodanno 2 Longhouse Poet 3 Delta Work 4 Roi Mage
A Grade One winner who could have run in the Cheltenham Gold Cup, Capodanno has been pointed here instead. Looks handicapped to run really well.