Henry Daly admits there is some doubt about Possol's participation in Saturday's Racing Post Chase at Kempton due to the possibility of soft ground.
The seven-year-old has been campaigned over hurdles so far this season with connections aiming for the Grand National at Aintree in April.
He is two from two since switching back to the smaller obstacles but Daly wants to get a run into his charge over fences sooner rather than later, otherwise the National dream may be over for another year.
"We've been playing over hurdles because I didn't want him to go up any more in the handicap as we're aiming at Aintree," Daly said.
"The ground on Saturday is a major worry for me and, basically, if it's soft ground he won't run.
"I'm very keen to run him if it's possible because it would fit in with my general plan of trying to run him in the National. If we don't run on Saturday it becomes about as clear as mud.
"He could run the following week in the Grimthorpe Chase at Doncaster but if he didn't go there for what ever reason, that might change our entire plan all together.
"We might easily end up running in the Albert Bartlett Novices' Hurdle at Cheltenham, and if we went there we probably wouldn't run in the National as I think it's a bit unfair to run him over hurdles three times and then ask him to go round Aintree."
Emma Lavelle is thrilled with the condition of her candidate Kilcrea Castle, who was third behind The Sawyer at Ascot on his first run since arriving from Ireland.
"He's absolutely bouncing and in great order," said Lavelle. "Jack (Doyle) was in this morning to work him and he went really well; his schooling is spectacular and I hope he goes there and runs a really big race."
Lavelle admits no decision has been made on Kilcrea Castle's participation in the John Smith's Grand National and she is in no rush to make any commitments.
"He's still a relatively young horse with a relatively small amount of experience," the trainer continued.
"I think the National is a race where you've got to be 100pc together and behind the horse to be having a crack at it.
"It's not a race for the faint-hearted and you still get some nasty falls, so we have to be certain that is the best thing to do and everyone needs to be happy that that's the route we're taking."
Paul Nicholls' sole success in the valuable chase came two years ago through Gungadu and the champion trainer will have just the one representative.
Fistral Beach, owned by Graham Roach, put a long line of seconds and thirds behind him when scoring at the Sunbury track in the middle of January.
"Fistral Beach goes to Kempton on Saturday," Nicholls said.