Vinci got past seventh-seeded Nadia Petrova 6-2, 1-6, 6-4. She won one more point -- 79-78 -- overall in the match but she was able to win on the strength of three third-set breaks.
She'll go against sixth-seeded Kaia Kanepi in the semifinals. Kanepi pulled a slight upset with a 6-3, 3-6, 6-3 win over fourth-seeded Petra Cetkovska. Kanepi finished off five of her six break-point chances, including 2-of-3 in the third set.
Knapp battled Galina Voskoboeva for nearly 3 hours before getting a 7-6 (7-4), 2-6, 6-4 win. Suarez Navarro had a relatively easy 6-3, 6-3 victory over Silvia Soler-Espinosa in her quarterfinal.
Vinci is 2-0 lifetime versus Kanepi, with both wins coming on clay. Suarez Navarro won the only time she played Knapp, but that was eight years ago.