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.
His withdrawal leaves the Paul Nicholls-trained Black Corton on his own at the top of the weights on 11st 12lb.
The seven-year-old, who will be ridden by Bryony Frost, finished second in the Charlie Hall Chase at Wetherby on his return to action.
Nicholls told At The Races: “He schooled on Wednesday morning and he was on fire – Bryony had a job sitting on him.
“He really is very well and that run at Wetherby has brought him on.
“It was a career-best performance (at Wetherby) and it puts him in the mix on Saturday. He’s a big price.
“He’s not the biggest and he’s carrying quite a lot of weight, but the weights are quite close this year and he’s very well.”
Colin Tizzard’s ante-post favourite Elegant Escape is next on the list. The Dorset-based trainer also saddles Sizing Tennessee and West Approach.
Thomas Patrick is another leading contender, after being beaten just half a length by Elegant Escape at Sandown three weeks ago, and trainer Tom Lacey is looking forward to the challenge.
He said: “I’d say Newbury could easily end up soft if they end up getting more rain.
“He doesn’t have to lead – he’ll be prominent – but that’s Richard Johnson’s job. You don’t tell Richard how to ride a horse.
“He’s pretty straightforward and he’s in great form. He did his last bit of proper work on Tuesday and Stan Sheppard, who has been riding him, says he feels better than ever.”
Alan King’s Dingo Dollar has been well backed in recent days following a pleasing comeback run over hurdles at Newbury.
“I was very pleased with his run over hurdles and everything has gone well since,” said King
“Obviously there’s a lot of rain around and he wouldn’t want the ground too soft. As long as it doesn’t get too desperate, I hope he’ll run well.
“Whether he’s classy enough to win a Ladbrokes Trophy I’m not sure, but I think he deserves to take his chance.”
Harry Fry saddles American, who will be ridden by 5lb claimer Aine O’Connor.
The Nigel Twiston-Davies-trained pair of Go Conquer and Flying Angel, Nicky Henderson’s Beware The Bear, Anthony Honeyball’s mare Ms Parfois, Richard Hobson’s Allysson Monterg and Neil Mulholland’s bottom weight The Young Master complete the line-up.