Barry Geraghty could miss tomorrow's Grand National at Aintree.
The Meath jockey, who had been due to ride Anibale Fly in the National, has been taken to Liverpool hospital with a suspected leg fracture after a fall in the Topham Chase this afternoon.
Geraghty was riding Peregrine Run and was still in contention when coming down late on. The eventual winner of that race was Cadmium, returning at a price of 8/1.
It was one of two winners for trainer Willie Mullins, who saddled 2/1 favourite Min to victory in the JLT Melling Chase.
After initial assessment, he was taken to hospital in an ambulance, missing the winning ride on Champ in the Grade One Doom Bar Sefton Novices' Hurdle, which went to Mark Walsh.
Champ's trainer Nicky Henderson said: "We have a nasty feeling that Barry has broken his leg, which would be tragic."
Walsh, like Geraghty retained by owner JP McManus, is currently due to ride Regal Encore.
Mark Enright was also taken to hospital following his tumble from Call It Magic at the Canal Turn.
Enright is also scheduled to ride in the National, on Gordon Elliott's Noble Endeavor.