Sunday's meeting at Exeter must pass an 8am precautionary inspection on raceday morning.
Waterlogging could be an issue at the Devon circuit, with up to 25 millimetres of rainfall forecast on Sunday morning.
The going is currently soft, good to soft in places.
Clerk of the course Barry Johnson said: "The rain is not due to get to us by 4am before clearing at around 11am.
"We can take some rain, but we won't be able to handle an inch of it."
The valuable meeting is due to feature an absorbing showdown between Puffin Billy and Melodic Rendezvous in the Bathwick Tyres Plymouth Novices' Hurdle.