Vinci, the No. 1 seed, lost the first two games in the match and then blasted past Michaella Krajicek 6-2, 6-0. The match lasted only 57 minutes.
Pennetta had an easy time disposing of Mariana Duque-Marino 6-0, 6-4. Pennetta won this tournament in 2005 and 2008 and has been a runner-up on four other occasions.
Sara Errani set up a semifinal meeting with Vinci by defeating Estrella Cabeza Candela 6-4, 6-3.
Pennetta's opponent in the semis will be Irina-Camelia Begu, who was a 6-1, 6-2 winner over Magdalena Rybarikova.
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