Ladbrokes World Hurdle hero More Of That will undergo a wind operation after losing his unbeaten record in disappointing fashion at Newbury last month.
Jonjo O'Neill's six-year-old looked a star when he lowered Annie Power’s colours for the first time in a pulsating contest at the Cheltenham Festival in March, but trailed home a distant third in the Long Distance Hurdle on his seasonal reappearance.
O'Neill hopes an operation will help his charge bounce back when he returns after the turn of the year.
"I don't know exactly when he'll have it done, but he's going to have a wind operation," said the trainer.
"It's something we had a few enquiries about last season, but he got away with it. We didn't need to do anything as long as he was winning.
"I don't know how long it will be (before he runs again), but it won't be this side of Christmas. It just depends how he comes back after (the operation).
"We'll see where we are in the New Year."
Another incumbent of Jackdaws Castle set a similar procedure is Merry King, who moved ominously into contention in the Hennessy Gold Cup, only to fade into third on the run to the line.
O'Neill said: "He's getting one (wind operation) done as well. I don't know how long it will keep him out. It depends what he has done. Hopefully not too long.
"It's something that stopped him a few times last year. Sometimes he got going again and sometimes he didn't.
"Hopefully we'll do a proper job on him and if everything goes well, the aim would be to go for the Grand National."
The trainer reports potential Cheltenham Gold Cup candidate Holywell to be none the worse after unseating Richie McLernon at Aintree on Saturday.
The seven-year-old struck gold at Cheltenham and Aintree last spring and was not disgraced on his return to action at Carlisle when third behind Hennessy winner Many Clouds and Peterborough Chase runner-up Eduard.
However, his jumping was already below par before he eventually unshipped his rider at the eighth fence on his return to Merseyside.
O'Neill said: "He's come back fine. It was no race really.
"I don't know where we'll go with him next. We'll wait and see."
