Rebecca Curtis' Teaforthree has been installed as the 7-1 market leader with the sponsors for the Coral Welsh National at Chepstow on December 27.
Officially, he would be the first Welsh-trained winner of the marathon since Norther in 1965, although Le Beau Bai (the 10-1 joint second favourite) was trained to land last year's contest by Richard Lee in the borders.
Teaforthree, who took the National Hunt Chase at the Cheltenham Festival over four miles last March, warmed up with an outing in the Henrietta Knight Handicap Chase at Cheltenham last weekend, won by another Chepstow entry in Monbeg Dude.
Giles Cross, who has been second in the last two renewals, is also among the 55 entries along with a useful Paul Nicholls team featuring Tidal Bay, Harry The Viking, Join Together, Royal Charm and Michel Le Bon.
A group of runners could cross from Ireland, as Willie Mullins has made entries for cross-county specialist Uncle Junior and Irish Hennessy winner Quel Esprit, while Becauseicouldntsee, Ardglen, Jadanli, Raz de Maree and Gordon Elliott's pair of Chicago Grey and Tharawaat could also be involved.
"Teaforthree proved his liking for a marathon trip when scoring at last season's Cheltenham Festival, and his recent reappearance behind Monbeg Dude and Bradley was a decent first step to Chepstow, where he would be an extremely popular home winner of Wales's greatest race," said Coral's David Stevens.