Former world number one Venus Williams, seeded seven, beat Australian Samantha Stosur 6-4 6-1 in a second-round game postponed from Tuesday because of rain to join Pironkova in the third round.

Fifth seed Serena Williams, who like her sister Venus is a former Italian Open champion, faces Ukrainian Alona Bondarenko later on Wednesday in another match that was bumped over from Tuesday.

Russian world number two Maria Sharapova will start her Rome campaign later against Slovak Dominika Cibulkova.