Tony McCoy's Grand National mount Synchronised could leave Ladbrokes with one of their biggest headaches in betting history.
predict the big race favourite and Cheltenham Gold Cup hero will attract tens of millions of pounds in bets on the big day.
David Williams of Ladbrokes said: "If the nation decides to trust in McCoy we could be staring down the barrel of some record-breaking liabilities on Synchronised.
"McCoy's win on Don't Push It in 2010 was one of the costliest days in our history but it could pale into insignificance if the mega money arrives for Synchronised."
And with Ruby Walsh's sister Katie having her first National ride aboard Seabass, the bookies suspect that the Irish-trained 9 year old could be the "housewives' choice."
"With half the adult population looking to have a flutter, Katie will have an army of fans. It would be a fairytale if she cooked the bookies with Seabass" said Williams.
The Grand National attracts over £300 million in bets on the biggest day of the bookmaking year.
Earlier this week, Ladbrokes reported West End Rocker and Shackalackaboomboom to be amongst the other most popular selections in the likely 40-runner field.
Ladbrokes latest betting on the Grand National: 6 Synchronised, 9 Junior, 10 Cappa Bleu, 10 On His Own, 11 West End Rocker, 12 Ballabriggs, 12 Giles Cross, 14 Seabass, 16 Killyglen, 16 Chicago Grey, 16 Sunnyhillboy, 16 Treacle, 20 Becauseicouldntsee, 20 Organised Confusion, 20 Shackalackaboomboom, 25/1 bar