Venus Williams of the U.S (Photo: Reuters)
Former world number one Venus Williams has been forced to withdraw from the Madrid Open due to a back problem, organizers said on Sunday.
The 32-year-old American, now ranked 21, was due to play her first-round match against Spanish wild card Anabel Medina Garrigues on the clay at the premier event on Sunday.
She will be replaced in the draw by 56th-ranked Stefanie Voegele of Switzerland.
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