Both Williams sisters were unable to get their Italian Open campaigns under way after persistent rain put an early end to play in Rome.
Only four matches were completed before a torrential downpour meant play was suspended at around 5pm local time.
Courts became flooded and at just after 9pm tournament organisers decided to call off the day's play and resume at 11am on Wednesday.
Both Williams sisters were due to begin their campaigns and will now play on Wednesday - weather permitting
Venus will play Australia's Samantha Stosur, while Serena will face Ukrainian doubles specialist Alona Bondarenko.
The top two seeds Ana Ivanovic of Serbia and Russia's Maria Sharapova are also due to play on Wednesday.
There was one shock on Tuesday as Austrian 19th seed Sybille Bammer was crushed by unseeded teenager Victoria Azarenka of Belarus 6-1 6-3.
Italy's Roberta Vinci gave the sparse and chilly crowds something to cheer about as she battled to a 6-4 4-6 6-0 victory over Estonian Kaia Kanepi.

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