Canterbury racing officials hope to be able to decide today whether the first day of their Grand National carnival takes place tomorrow.
Canterbury Jockey Club chief executive Tim Mills said the contingency plan was to move to Sunday if the current stormy weather ruled out racing tomorrow.
The track was yesterday a heavy 11 - the worst rating possible - after 50mm fell overnight and drizzly rain continued into the afternoon.
"The track's drainage system is coping with it adequately today, but we probably could not handle it if another 50mm was dumped on it straight away," Mills said.
The track's major soak pit had been extended to cope with the increased drainage and "various pumping experts are shifting water off the track as best they can".
A decision whether to race would likely be made late today, but again that would be dependent on the weather.
"I've looked at five weather forecasts and they are all different. I am going with the optimistic one which has got showers clearing tomorrow and a good fine day on Saturday and again on Sunday," Mills said.
"But everyone I speak to has heard a different forecast, so we are in the lap of the gods and have to wait and see."
Most North Island visitors were already in the region, he said.
A likely casualty from the Winter Cup is Capecover, a $7 chance on the TAB last night.
Trainer Alexander Fieldes said he would be reluctant to start the horse on a track as bad as the one predicted for Saturday.