Kemboy will miss the Ladbrokes Trophy at Newbury on Saturday due to travel problems.
The six-year-old emerged as a leading contender for the prestigious handicap — formerly known as the Hennessy Gold Cup — when making a successful start to his campaign in the Clonmel Oil Chase a fortnight ago.
Irish champion trainer Willie Mullins, who won last year's renewal with Total Recall, had seven contenders at Monday's confirmation stage, but Kemboy was his only declared runner.
The Supreme Horse Racing Club-owned gelding was due to make the trip across the Irish Sea on Thursday morning, but with his ferry cancelled and delays possible for later ferries, plans were abandoned.
Steve Massey, racing manager for the owners, said: “It’s obviously very disappointing.
“We were looking forward to having a horse with a leading chance in such a prestigious race, but we can’t do anything about the weather.
“The ferry was cancelled this morning and the ferries later tonight could be delayed. Even if he did get a ferry late, he could have a rough trip and might not get to Newbury until the early hours of the morning.
“It’s a big blow and disappointing for all his owners, but we know he’s an exciting horse and we have to do what is in his best interests.”
Kemboy was the 9-2 favourite for historic handicap following the final declaration stage.
