Manx Radio understands tomorrow evening's first Manx Grand Prix practice is in "severe danger" of being cancelled because of a lack of marshals.
It's believed nine of the twelve sectors on the Mountain Course are short of adequate cover.
If this situation remains the same, the Clerk of the Course will have no option but to call off the session.
Roads are due to close at six o'clock tomorrow evening to re-open no later than 8.45pm.
The Isle of Man T.T. Marshals Association office at the back of the Grandstand is open until seven o'clock this evening, and will re-open at nine o'clock tomorrow morning.
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