Ante-post favourite Allaho will miss the Ladbrokes King George VI Chase at Kempton Park on Boxing 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.
Instead, the champion trainer 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."
Mullins also subsequently confirmed to the PA news agency that Allaho would miss Kempton.
