Doncaster's card on Saturday featuring the final Group One of the British season - the Vertem Futurity Trophy - must survive a 7.30am precautionary inspection.
While there was no problem with Friday's meeting going ahead, heavy rain was forecast to move in from midday onwards and continue through the day and into the night.
As a result, clerk of the course Roderick Duncan felt it prudent to call an inspection to make people aware of the situation.
"The rain has been developing all morning. Some forecasts suggested we were on the edge of it, but as the morning has gone on we seem to be more in the centre of the rainfall," said Duncan.
"We've in excess of 10 millimetres forecast from midday today with the potential for getting on for 30 millimetres overnight and into tomorrow on top of that. Because of that we thought it best to call an inspection and give everybody a heads up. It just seems we've moved from the edge of the band into the centre of it and the percentage chance of getting all that rain has risen."
Newbury also inspect
Saturday's meeting at Newbury is subject to a precautionary inspection at 8am due to the threat of further rain.
Conditions at the Berkshire circuit were described as heavy during Friday's card and clerk of the course Keith Ottesen plans to check the ground is raceable ahead of Saturday's fixture.
He told Racing TV: "Based on feedback from the jockeys about how the track has been riding today - and given we've got more rain forecast from mid-morning onwards - we're going to have a precautionary inspection at 8am.
"To say the jockeys are happy with it isn't correct. They're happy to carry on today, but they've all resoundingly said that if we got much more rain on that ground overnight, we could be in trouble.
"Fingers crossed it misses us or moves aside, but we need to let people know from around 8am once we've got some daylight on it."
