Rome - Top-ranked Serena Williams has withdrawn from the Italian Open.
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Tournament organizers announced Williams' decision without explanation shortly before she was scheduled to face fellow American Christina McHale, a qualifier, in the third round.
Williams was scheduled to meet with reporters later.
In her opener Tuesday, Williams cruised past 39th-ranked Anastasia Pavlyuchenkova 6-1, 6-3 in just over an hour.
The Italian Open is the last major warmup for the French Open, which starts in 10 days.
Williams is the defending champion at the Foro Italico.