Barry Geraghty will miss his ride on Anibale Fly in the Randox Health Grand National after suffering a broken leg in a fall from Peregrine Run in the Topham Chase at Aintree on Friday.
Geraghty's mount was still contention when coming down late on in the race over the National fences, and the rider was taken to hospital for further assessment, missing the winning ride on Champ, with Mark Walsh stepping in for the mount.
He had been looking forward to a leading chance in the National, as Anibale Fly finished runner-up to Al Boum Photo in the Gold Cup at Cheltenham last month and was fourth in the 2018 renewal of the Aintree spectacular.
Speaking on Friday evening, he told attheraces.com: "It's bad news, unfortunately. I was hurt after Peregrine Run fell in the Topham Chase earlier today and it has been confirmed that I have broken both my tibia and fibula just above my right ankle.
"I haven't seen a replay of the fall yet, but by the sounds of it, it might have been a kick off a horse that ran over the top of me after the fall that did the damage."
He added: "It's a real sickener to miss tomorrow as the Grand National is the race I look forward to more than any other, but missing Fairyhouse and Punchestown too is just as sickening."
"In terms of when I'll be back, it's too early to say. It's probably going to need surgery to straighten it. It's a weight-bearing bone and it took me nearly four months to come back when I broke my shin on the other leg a few years ago.
"I'd only be guessing at this stage, but I'll probably be at least 10 to 12 weeks on the sidelines."
Mark Enright was also taken to hospital following his tumble from Call It Magic at the Canal Turn in the Topham.
Enright is booked to ride Noble Endeavor for Gordon Elliott in the National.