Ante-post favourite Allaho will miss the Ladbrokes King George VI Chase at Kempton Park on St Stephen's Day.
The Willie Mullins-trained eight-year-old enjoyed the perfect season last term, winning his second Ryanair Chase and proving his versatility at Punchestown when winning over three miles in fine style.
He had been a short price to add the Christmas highlight to his impressive record, but the Cheveley Park Stud-owned chaser will not be ready in time due to a setback.
Mullins had mooted next week's Clonmel Oil Chase on as a potential starting point but his name was not among the entries this week and the champion trainer confirmed that Allaho would miss Kempton..
Instead, Mullins entered King George winner Tornado Flyer, Blue Lord and Haut En Couleurs for the Grade Two.
The owners do have an able second string for Kempton in the shape of Saturday’s Down Royal Champion Chase winner Envoi Allen.
Richard Thompson, Cheveley Park director, told Sky Sports Racing: "We have had a great run with these horses but these things happen. Envoi will go for the King George.
"We’ve won 23 Grade Ones in four years and counting, from only a few horses. Everything now is a bonus."
Meanwhile, Mullins unleashes two of his big hopes for the season this weekend, with a top-class couple of days in store in Ireland.
He again has an arsenal of riches for every department, but it is his sharper chasers who take centre stage with Gentleman De Mee in action at Naas on Saturday before Ferny Hollow reappears at Navan on Sunday.
The JP McManus-owned Gentleman De Mee has won the last three of his five outings over fences and was last seen flooring Arkle hero Edwardstone at Aintree.
He is set to face four rivals in the Barberstown Castle Poplar Square Chase, a Grade Three over two miles - before a potential clash with Shishkin next month.
"He is in good shape, but his Grade One penalty won't help him. Hopefully it will put him right for the Tingle Creek, but it is a tough old race," said the Closutton handler.
Ferny Hollow remains one of the most exciting horses in training when he is right. He returns to the track for the first time since December when he tackles the Grade Two Sean P Muldoon & Patrick F Gormley Fortria Chase, where his opponents include Gordon Elliott's smart mare Riviere D'etel.
Mullins said: "He has to start off somewhere and fingers crossed he stays sound this year. I'm looking forward to him."
Mullins also has an interest at Cheltenham on Sunday, with Dads Lad in the Unibet Greatwood Hurdle.
The seven-year-old was a winner over fences at the October fixture and Mullins added: "He likes the track and I think the ground is right for him. We are hoping for the best that lightning can strike twice in one place."
