Full Timeform runner-by-runner guide...
1. THE LAST SAMURI (Kim Bailey/David Bass)
Has barely put a foot wrong in his career so far, and jumped superbly when six lengths second to Rule The World in last year's Grand National. Close third behind Vieux Lion Rouge and Highland Lodge back over these fences in the Becher in December and second to Definitly Red in the Grimthorpe at Doncaster last time. Lot more weight to carry this year, but capable of going close again.
2. MORE OF THAT (Jonjo O'Neill/Barry Geraghty)
Won World Hurdle in 2014 and not had much racing since over fences, winning first two starts as a novice. Looked back on good terms with himself before falling at the last in Irish Gold Cup and not disgraced when sixth in Cheltenham Gold Cup last time.
3. SHANTOU FLYER (Rebecca Curtis/Jonathan Moore)
Only a seven-year-old but plenty of chasing experience, mostly for Colin Bowe in Ireland. Winning debut for new stable at Cheltenham on New Year's Day but predictably no match for Cue Card in Ascot Chase last time. Showed he stays 3m for former yard, but any further an unknown.
4. PERFECT CANDIDATE (Fergal O'Brien/Paddy Brennan)
Ran well when narrowly beaten in a Cheltenham Grade 3 handicap in December. Pulled up next time but got back to winning ways returned to forcing tactics in a veterans' chase at Exeter last time. Jumped superbly that day so could outrun long odds.
5. SAPHIR DU RHEU (Paul Nicholls/Sam Twiston-Davies)
Might not have gone on from his novice season over fences in 2014/15 (Grade 1 winner at Aintree) but has run well on all four completed starts this season, easily landing odds in a minor chase at Kelso and running a cracker when fifth in Cheltenham Gold Cup on last two. Stamina not assured but potentially well-in at the weights.
6. ROI DES FRANCS (Gordon Elliott/Jack Kennedy)
Winner twice as a novice last term for Willie Mullins, including Grade 2 at Naas. Back on track in blinkers in minor contest at Down Royal last time, albeit in uncompetitive event. Should stay long distances, though ground might not been soft enough.
7. WOUNDED WARRIOR (Noel Meade/Sean Flanagan)
Over two years since last win in Grade 2 novice at Naas (when beating future Grand National winner Rule The World) but mixed fortunes since, headgear in recent starts failing to spark a revival.
8. WONDERFUL CHARM (Paul Nicholls/Ms Katie Walsh)
Very smart chaser at one time but ran no sort of race in last year's Grand National. Fared better in calmer waters of hunter chases this season, winning first two starts and only narrowly beaten coming from well back in Foxhunter at Cheltenham last time. Tougher task again here.
9. TENOR NIVENAIS (Venetia Williams/Liam Treadwell)
Front runner who gained reward for consistency when winning a handicap chase at Ascot in February, though beaten at odds on in listed event at Kelso since. Potentially on a good mark but not proven beyond 3m and wouldn't want conditions to dry out.
10. BLAKLION (Nigel Twiston-Davies/Noel Fehily)
Reliable sort who won three of his seven starts as a novice chaser last term, including the RSA. Third to Definitly Red in Rowland Meyrick at Wetherby before better than ever when second to Vieux Lion Rouge at Haydock last time. Sound-jumping stayer so realistic claims of being involved.
11. DROP OUT JOE (Charlie Longsdon/Tom O'Brien)
Dual winner in autumn 2015, including Badger Ales Trophy at Wincanton, and back to form to take well-contested Summer Cup at Uttoxeter last June. Absence since then to overcome and seemed not to get home in Scottish National couple of years ago.
12. LE MERCUREY (Paul Nicholls/Sean Bowen)
Won three times as a novice chaser last season. Runner-up in small-field contests this term behind Many Clouds at Aintree and Native River at Newbury but stamina concerns after seemingly not getting home over 3m in heavy ground at Kelso last time.
13. THE YOUNG MASTER (Neil Mulholland/Mr Sam Waley-Cohen)
Placed in valuable handicap chases at Ascot and the Cheltenham Festival last season before gaining his reward in bet365 Gold Cup at Sandown. Beaten when falling in Becher Chase on reappearance (well held over hurdles next time), but much better when sixth in Ultima Handicap at Cheltenham since and certainly worth a try over this longer distance.
14. CAUSE OF CAUSES (Gordon Elliott/Mr Jamie Codd)
Eighth in 2015 Grand National but missed the cut last year. Winner at Cheltenham Festival for third year running when bouncing back to form in Glenfarclas (cross-country) Chase last time and prospects of bettering previous try here when left with plenty to do.
15. REGAL ENCORE (Anthony Honeyball/Robbie Power)
All-or-nothing record, highlight being listed handicap win at Ascot just before Christmas. Pulled up next time and hard to know how he'll fare after a break, though has at least looked worth a try over this sort of trip.
16. VIEUX LION ROUGE (David Pipe/Tom Scudamore)
Very smart chaser who wore down previous winner Highland Lodge in dying strides of Becher Chase over these fences in December. Impressive winner of Grand National Trial at Haydock since from Blaklion, so every chance of going much closer than last year (faded to seventh) when still a novice.
17. DEFINITLY RED (Brian Ellison/Danny Cook)
Three-time winner this season, over hurdles at Carlisle and over fences at Wetherby (had Blaklion back in third in Rowland Meyrick) and Doncaster, producing another career-best when beating The Last Samuri 14 lengths in Grimthorpe Chase for latest success. Usually a sound jumper and worth a try over this marathon distance, so very much a leading contender.
18. UCELLO CONTI (Gordon Elliott/Daryl Jacob)
Yet to win since coming from France but several good efforts in competitive handicap chases, overcoming bad mistake when sixth in last year's Grand National. Placed in Thyestes Chase at Gowran for second year running in January and latest start when fourth in Leinster National at Naas should have brought him on with this in mind.
19. DOUBLE SHUFFLE (Tom George/Adrian Heskin)
Has progressed since being stepped up to 3m and wearing a hood on his last two starts at Kempton, winning on first occasion and finishing half-length second to Pilgrims Bay in BetBright Chase last time. In good form but question mark over him staying this far.
20. HOUBLON DES OBEAUX (Venetia Williams/Charlie Deutsch)
Thorough stayer who goes well in the mud, winning Denman Chase at Newbury last term and making the frame this season in Welsh National, Classic Chase at Warwick and Midlands National at Uttoxeter. Danger he might find things happening a bit quickly, however.
21. PLEASANT COMPANY (Willie Mullins/Ruby Walsh)
Raced freely before being pulled up in National Hunt Chase at Cheltenham last March but has worn hood since and won valuable chases on two of his last three starts, including Bobbyjo Chase at Fairyhouse in February from Thunder And Roses. Unexposed as a stayer.
22. ONE FOR ARTHUR (Lucinda Russell/Derek Fox)
Has improved this season, winning at Kelso and Warwick, relishing first try over a marathon trip when easily winning Classic Chase in January at latter track. Fifth in Becher Chase other start this season gave him experience of these fences, and more progressive than most in the field.
23. BALLYNAGOUR (David Pipe/David Noonan)
Unseated after halfway in last year's Grand National. Couple of good seconds in decent handicaps last summer, including behind Drop Out Joe at Uttoxeter, but has looked badly out of sorts more recently.
24. O'FAOLAINS BOY (Rebecca Curtis/Paul Townend)
Former RSA winner who ran well for a long way in last season's Cheltenham Gold Cup. Potentially thrown-in from current mark, though pulled up on both starts this term and needs recent breathing operation to have worked wonders.
25. HIGHLAND LODGE (James Moffatt/Henry Brooke)
Overall record none too reliable and lightly raced of late but two fine efforts in Becher Chase over these fences to his name, winning on stable debut in 2015 and collared on line by Vieux Lion Rouge when looking all set for repeat win in December. Kept fresh since and entitled to respect.
26. BISHOPS ROAD (Kerry Lee/Jamie Moore)
Won twice early in 2016 for new stable, notably Grand National Trial at Haydock, but not high enough in weights to make National field (unseated first in Topham instead). Encouraging fourth in Rehearsal Chase at Newcastle on return but not built on that either start since.
27. LORD WINDERMERE (Jim Culloty/Leighton Aspell)
Won the Cheltenham Gold Cup in 2014. Clearly had his problems since, pulled up in a first-time visor in last year's Grand National and failing to go on from his encouraging return this season, though lot less weight to carry this year.
28. SAINT ARE (Tom George/Davy Russell)
Runner-up in 2015 Grand National but pulled up last year when jumping let him down, as it did when falling heavily at first in Becher Chase earlier this season. Best effort this term when close second in bid to win veterans chase at Doncaster last time for second year running.
29. VICENTE (Paul Nicholls/Brian Hughes)
Won four of his seven starts as a novice last season, most notably Scottish Grand National at Ayr. Hasn't fired yet in good staying handicaps this season and needs to avoid jumping errors, but dropped a bit in weights and not a complete surprise to see him perform a fair bit better here.
30. JUST A PAR (Paul Nicholls/Harry Cobden)
Won the bet365 Gold Cup at Sandown in 2015 and gained first win since in a veterans handicap at Newbury in March when everything fell right for him. Struggled in two previous tries over these fences, including in National itself last year, so looks up against it.
31. MEASUREOFMYDREAMS (Noel Meade/Donagh Meyler)
Won his first two outings over fences last winter before finishing third in 2016 National Hunt Chase at Cheltenham when still with Willie Mullins. Harder to recommend on more recent efforts though.
32. RAZ DE MAREE (Gavin Cromwell/Ger Fox)
Won Cork Grand National for second time in November and even better form when second to Native River in Welsh National at Chepstow, faring best of those held up and well clear of the rest. Warmed up with second over hurdles since, and got round in previous attempt here three years ago.
33. STELLAR NOTION (Henry de Bromhead/David Mullins)
Listowel winner over 19f last summer on first start since leaving Paul Nicholls. Made the frame in better handicaps since but strong-travelling type up to 3m who races prominently so doubts about him staying this far.
34. ROUGE ANGEL (Mouse Morris/Bryan Cooper)
Same connections as last year's winner Rule The World. Three wins last season included Irish Grand National at Fairyhouse but little impact this term (including in Becher here in December), though fifth in Thyestes last time was one of better efforts.
35. COCKTAILS AT DAWN (Nicky Henderson/Nico de Boinville)
Gave weight and beating to a good field (Blaklion included) in novice at Chepstow in autumn 2015, but jumping has let him down since, including in Topham over these fences last year, and unproven beyond 21f to boot.
36. THUNDER AND ROSES (Mouse Morris/Mark Enright)
Not won since 2015 Irish Grand National when with Sandra Hughes, though ran Pleasant Company close in Bobbyjo Chase back at Fairyhouse in February. Not in same form last time, but stable won this last year and can be excused previous attempt over these fences.
37. GAS LINE BOY (Ian Williams/Robbert Dunne)
Front-runner who's held his form well this season since joining current yard. Easy winner of veterans' handicap at Kelso in December and far from discredited forcing pace when fourth to Vieux Lion Rouge in Grand National Trial at Haydock last time.
38. GOODTOKNOW (Kerry Lee/Jake Greenall)
Thorough stayer who was no match for One For Arthur in Classic Chase at Warwick but went one better in heavy ground at Hereford next time. Excuses when pulled up in Grand National Trial last time but likely to find conditions too quick again here.
39. LA VATICANE (David Pipe/Richie McLernon)
As good as ever when winning at Doncaster in December. Last start can be ignored when badly hampered in Kim Muir at Cheltenham but faces much her stiffest test to date, though has at least completed in both attempts over these fences.
40. DOCTOR HARPER (David Pipe/Conor O'Farrell)
Had good strike-rate over hurdles earlier in career, including a win at this meeting. More of a mixed record over fences, though went close at Cheltenham on New Year's Day and respectable seventh in Kim Muir there last month.
Timeform Grand National 1-2-3:
1. Definitly Red
2. Vieux Lion Rouge
3. Ucello Conti
Timeform Grand National Analyst's Verdict:
DEFINITLY RED's position at the head of the betting looks well and truly justified after his beating of last year's runner-up The Last Samuri at Doncaster and he can end the run of big-priced winners with a historic victory. Vieux Lion Rouge has improved plenty since his seventh 12 months ago and can go well, while a strong Irish challenge is headed by Ucello Conti and Pleasant Company.