Norman Williamson will replace the injured Paul Carberry on Harbour Pilot in the Punchestown Heineken Gold Cup tomorrow.
Carberry is currently sidelined with a badly bruised thigh leaving Williamson to step in for the mount.
But trainer Noel Meade said the horse - who finished third in this year's Cheltenham Gold Cup - would miss the Grade One contest if underfoot conditions were not suitable.
He said: "We would need all the rain we can get between now and then. If it dries up he won't run. He runs if there's enough juice in the ground. They say it's good to yielding today but it will want to be every bit of that tomorrow for him to run."
Nine horses have been declared for the contest. Local hopes also rest with Beef Or Salmon, Native Upmanship, last year's winner Florida Pearl, Foxchapel King and Ted Walsh's Rince Ri.
Oversees challengers Hussard Collonges, Young Spartacus and back-to-form chaser First Gold complete the line-up.