Barry Geraghty admits "it's a tricky one" as he ponders between More Of That and Cause Of Causes as his mount in the Randox Health Grand National at Aintree on Saturday.
JP McManus' retained No 1 rider, who only returned from injury on Sunday, is likely to delay his decision until as late as possible.
Though McManus could also represented by the Charlie Longsdon-trained Pendra and Anthony Honeyball's Regal Encore in the big race, Geraghty has narrowed down his choice to two.
The Jonjo O'Neill-trained More Of That was sixth in the Cheltenham Gold Cup, while Gordon Elliott's Cause Of Causes won the Glenfarclas Cross Country Chase at the Festival.
"I'm none the wiser at the minute. I've sat on both horses." Geraghty told At The Races. "I rode Cause Of Causes work last week and he felt well. I schooled More Of That on Friday and that went well, too. Both are in good shape.
"You can make a very good case for both horses, so I'm a little bit undecided at the minute. More Of That was running well at Leopardstown when he can down at the last. You have to think he disappointed a little in the Gold Cup, but you'd like to think he's better than that.
"Cause Of Causes obviously won the cross-country race in Cheltenham and that has been a good indicator over the years, but off his handicap mark it could be hard for him.
"It's a tricky one. It's not a straightforward one. I'll make my decision on Thursday or shortly before. I can't imagine it being too long before Thursday."
Aidan Coleman and Jamie Codd are among the riders McManus can also call upon.
"Aidan Coleman will ride one and possibly Jamie Codd," said the owner's racing manager, Frank Berry. "If the ground stays like it is, Regal Encore will probably run as well. At the minute we could have four runners."
Full list of runners and riders
A maximum of 40 horses will race. All horses are British unless stated
All the entries have a Telegraph star rating, which reflects their chance based on previous form and suitability to the race. The horse with the best chance has five stars and those with the worst have one star.
Horse, age, weight, trainer & rating
THE LAST SAMURI (IRE), 9, 11-9, Kim Bailey (161) **** 16/1
Excellent second a year ago and looks even better this year; looks sure to make another bold bid.
MORE OF THAT (IRE), 9, 11-5, Jonjo O'Neill (157) ** 12/1
Fair sixth in Cheltenham Gold Cup last time and has touch of class; better since fitted with cheekpieces.
PERFECT CANDIDATE (IRE), 10, 11-4, Fergal O'Brien (156) ** 50/1
Often front runs; stays and jumps well and acts on any going.
SAPHIR DU RHEU (FR), 8, 11-4, Paul Nicholls (156) **** 20/1
In good form this season and ran his best race for years when fifth in Gold Cup; has not fallen since 2014.
SHANTOU FLYER (IRE), 7, 11-4, Rebecca Curtis (156) *** 66/1
Stays 3m but yet to tackle extreme distances; likes good ground or softer.
ROI DES FRANCS (FR), 8, 11-2 Gordon Elliott (154) * 50/1
Stays well and showed benefit of blinkers first time when winning comfortably on latest outing.
WONDERFUL CHARM (FR), 9, 11-1, Paul Nicholls (153) ** 40/1
Has had his enthusiasm rekindled in hunter chases; ran right up to best when second at Cheltenham last time; best on good ground.
WOUNDED WARRIOR (IRE), 8, 11-1 Noel Meade (153) * 66/1
Consistent and capable stayer but not a prolific winner; good jumper and should get around.
BLAKLION, 8, 11-0, Nigel Twiston-Davies (152) **** 14/1
Classy and holds his form well. Ran a fine race when second in Haydock’s Grand National Trial. Likes fast ground.
DROP OUT JOE, 9, 11-0, Charlie Longsdon (152) *** 50/1
Has only run 12 times in past 3 years so has had injury issues but definitely has ability; good ground is best.
TENOR NIVERNAIS (FR), 10, 11-0, Venetia Williams (152) * 40/1
Useful on his day and likes to race up with pace, which could well add to his stamina issues.
LE MERCUREY (FR), 7, 10-13, Paul Nicholls (151) * 40/1
Fair performer but does not win often and stamina has to be taken on trust.
CAUSE OF CAUSES (USA), 9, 10-12, Gordon Elliott (150) *** 14/1
Looks a likely type and won nicely over Cheltenham’s Cross Country track last time; stamina not an issue and ground should suit.
REGAL ENCORE (IRE), 9, 10-12, Anthony Honeyball (150) ** 50/1
Inconsistent but capable on a going day; best form on fast ground.
THE YOUNG MASTER, 8, 10-12, Neil Mulholland (150) ** 20/1
Won Bet365 Gold Cup last spring so stamina not an issue. Out of form since, including when falling 2 out here in December; showed a bit more last time.
DEFINITLY RED (IRE), 8, 10-11, Brian Ellison (149) *** 11/1
Generally progressive and we have probably yet to see the best of him; impressive when beating The Last Samuri at Doncaster; strong player.
DOUBLE SHUFFLE (IRE), 7, 10-11, Tom George (149) ** 40/1
On the upgrade and a likeable sort; acts on any ground; looks capable of playing his part.
HOUBLON DES OBEAUX (FR), 10, 10-11, Venetia Williams (149) * 50/1
Smart chaser once but age is catching up with him; fourth in last year’s Midlands Grand National at Uttoxeter.
PLEASANT COMPANY (IRE), 9, 10-11, W. P. Mullins (149) *** 16/1
Improving and looks to have been targeted at this race; a solid jumper who seems to go on any ground.
UCELLO CONTI (FR), (27), 9, 10-11 Gordon Elliott, Ireland (149) ** 18/1
Fair performer but has not won since moving to Ireland and not since 2014 in France; 6th a year ago and aimed at this since.
VIEUX LION ROUGE (FR), 8, 10-11, David Pipe (149) **** 11/1
Proven over the fences and this tough stayer, who appears to act on most types on gound, must be respected.
BALLYNAGOUR (IRE), (70), 11, 10-10, David Pipe (148) * 66/1
Was once smart but is hard to predict these days. Unseated rider at 19th fence last year.
HIGHLAND LODGE (IRE), 11, 10-10, James Moffatt (148) *** 25/1
Has a good record over the fences in three attempts with form figures of 812 and this has been his target all season; bold show expected.
O'FAOLAINS BOY (IRE), 10, 10-10, Rebecca Curtis (148) * 66/1
Appears to have lost his way this season and has in fact not won since December 2015; hard to fancy.
ONE FOR ARTHUR (IRE), 8, 10-10, Lucinda Russell (148) *** 14/1
Third to Vieux Lion Rouge here in December and then won over 3m 5f at Warwick when wearing a tongue tie for the first time.
BISHOPS ROAD (IRE), 9, 10-9, Kerry Lee (147) * 66/1
Fair performer but has become prone to jumping mistakes and came down at the first over these fences at last year’s meeting.
LORD WINDERMERE (IRE), 11, 10-9, Ireland (147) * 50/1
Won 2014 Cheltenham Gold Cup but is on the downgrade these days. Got as far as the 24th fence 2 years ago before pulling up.
SAINT ARE (FR), 11 10-9, Tom George (147) ** 40/1
Finished second two years ago but has failed to finish on past two attempts over the fences. Looked close to best when second last time.
VICENTE (FR), (49), 8, 10-9, Paul Nicholls (147) *** 25/1
Won 2016 Scottish Grand National but disappointing since. However, his record suggests he is a spring horse and he could easily bounce back.
JUST A PAR (IRE), 10, 10-8, Paul Nicholls (146) ** 40/1
Finished 15th when a 40/1 chance in last year’s race. Returned to form at Newbury recently; good jumper.
MEASUREOFMYDREAMS (IRE), 9, 10-8, Noel Meade, Ireland (146) ** 50/1
Favourite when an early faller in 2016 Scottish Grand National; lightly-raced this season and ran with some promise at Cheltenham last time.
RAZ DE MAREE (FR), 12, 10-8, Gavin Patrick Cromwell, Ireland (146) *** 33/1
Finished 8th in 2014 National but improved since; has twice won Cork Grand National and finished second in Welsh National last December; solid stayer.
STELLAR NOTION (IRE), 9, 10-8, Henry de Bromhead, (146) * 50/1
Normally races at short of 3m and has yet to prove he has the stamina for a contest such as this.Best on decent ground.
COCKTAILS AT DAWN, 9, 10-7, Nicky Henderson (145) * 100/1
Has a very patchy profile and fell in last year’s Topham (2m 5f) over the fences; unproven in stamina department.
PENDRA (IRE), 9, 10-7, Charlie Longsdon (145) * 50/1
Was a 50-1 chance when a distant 13th a year ago but ran really well on only start since, when wearing blinkers for first time.
ROGUE ANGEL (IRE), 9, 10-7, M. F. Morris, (145) ** 33/1
A brave winner of 2016 Irish Grand National; well behind Vieux Lion Rouge here in December and might need softer ground.
GAS LINE BOY (IRE), 11, 10-6, Ian Williams (144) * 66/1
Fell at the first when a 66/1 chance in 2015. Relatively consistent and stays well enough. Enjoys decent going.
GOODTOKNOW, 9, 10-6, Kerry Lee (144) ** 66/1
Stays well but is an in-an-out-perofmer who tends to throw in a really poor run from time to time. Seems to act on any going.
THUNDER AND ROSES (IRE), 9, 10-6, M. F. Morris (144) ** 40/1
Has not won since landing the 2015 Irish Grand National although has run some fair races. Best with some give in the ground.
LA VATICANE (FR), 8 10-5, David Pipe (143) * 100/1
Has twice got around over these fences but in much shorter races and stamina has to be an issue.
DOCTOR HARPER (IRE), 9, 10-5, David Pipe (143) 66/1
BLESS THE WINGS (IRE), 12, 10-4, Gordon Elliott (142) 50/1
KNOCK HOUSE (IRE), 8, 10-3, Donald McCain (141) 66/1