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Only four matches were completed before a torrential downpour suspended play at around 5pm local time.
Courts became flooded but light rain never abated and at just after 9pm tournament organisers decided to call off the day's play and resume at 11am on Wednesday.
Austrian 19th seed Sybille Bammer was the highest ranked player to finish a game but she was easily dismissed by Victoria Azarenka of Belarus 6-1, 6-3.
Home favourite Roberta Vinci gave the sparse crowds something to cheer about as she battled to a 6-4, 4-6, 6-0 victory over Estonia's Kaia Kanepi.
Both Williams sisters were due to begin their campaigns in the second round but will now have to wait until Wednesday to take to the courts.
Venus will play Australia's Samantha Stosur while younger sister 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.
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