James Motherway has been forced to rule Bluesea Cracker out of Saturday's rearranged Coral Welsh National at Chepstow.
Last season's Irish Grand National winner had been third-favourite with the sponsors at 9/1 following a decent run behind Midnight Chase at Cheltenham in November.
However, the nine-year-old mare knocked herself when walking in the sea near Motherway's Co Cork yard last week and the injury has not settled down in time for her to take her chance.
"Unfortunately last Thursday morning she was having a little bit of exercise on the beach nearby and she just took a false step in the water and knocked into her front joint," said Motherway. "It's not going to rectify itself in time for the weekend.
"I've just had a consultation with my vet who checked it again and he's not happy with it so we've had to draw a line through it unfortunately.
"If the race had been run on its correct date (December 27) she'd have been there, but there's nothing you can do about it. It's unfortunate.
"It's nothing serious but it's enough to put us out of Saturday's race.
"She loves it soft so it looked the ideal race for her.
"I've nothing concrete in the pipeline and I'll just see how this joint settles down over the next week or two."
Noel Meade has withdrawn Pandorama, but Willie Mullins could still be represented by Arbor Supreme.
Coral Welsh National -- sponsors bet: 11/2 Synchronised, 8/1 Maktu, 12/1 Dance Island, Dream Alliance, Watamu Bay, Summery Justice, 14/1 Silver By Nature, 16/1 Exmoor Ranger, Hello Bud, Master Overseer, 20/1 Arbor Supreme, I'moncloudnine, 25/1 Giles Cross, 33/1 Bar