Saturday's meetings at Uttoxeter and Kempton must both pass precautionary inspections at 8am as forecast stormy weather threatens to play havoc with the weekend action.
Uttoxeter is due to stage the Marstons 61 Deep Midlands Grand National as part of its eight-race card, but officials are concerned by the prospect of strong winds.
A statement from the track said: "We still anticipate strong winds tomorrow, peaking at around 40 miles per hour, but remain optimistic about being able to race. We will continue to monitor conditions and hold a precautionary inspection at 8am tomorrow to consider the most up to date forecasts for the rest of the day."
It is a similar story at Kempton, which is due to feature some richly-endowed Cheltenham consolation races.
The track tweeted: "In view of the forecast gale force wind tomorrow morning, we will hold a precautionary inspection at 8am to monitor and assess the safety of all concerned ahead of racing on @TeamMatchbook Silver Cups Day."
Sunday's Ffos Las card is also under threat with further rain expected on already heavy ground.
Officials at the Welsh venue will assess conditions at 8.30am on Saturday.
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