John Smith's Grand National hope Organisedconfusion has sustained a leg injury and is out for the rest of the campaign.
However, trainer Arthur Moore expects the eight-year-old to be back in action next season.
"He has a hairline fracture in his off-hind pastern bone," said the Naas handler.
"He will make a full recovery for next season, but he's out for the rest of this
The injury was discovered after he ran in the Leopardstown Handicap Chase last weekend.
Organisedconfusion, a top-priced 40-1 for the Aintree showpiece, won the Irish Grand National at Fairyhouse in April 2011.