Surprise packages Zarina Diyas and Christina McHale will face off in the quarter-finals of the Internationaux de Strasbourg.
Diyas - the world No 98 from Kazakhstan - followed up her shock dismissal of third seed Kirsten Flipkens by beating Croatia's Ajla Tomljanovic 6-4 7-6 (7/4) on Wednesday.
She next meets McHale after the American won 6-3 7-5 to add Casey Dellacqua of Australia to her list of victims following a first-round triumph over fifth seed Elena Vesnina.
Madison Keys claimed the scalp of eighth-seeded Alison Riske - the Florida-born player is now preparing to tackle Germany's Julia Goerges after conquering her fellow American 6-4 6-4.
Goerges made the last eight with a 7-5 6-4 win against Lauren Davis.
Camila Giorgi emerged victorious from a gruelling near three-hour encounter with home hopeful Claire Feuerstein and her reward for securing a 5-7 7-5 7-6 (7/2) victory is a quarter-final meeting with Silvia Soler-Espinosa.
The Spaniard also had to play three sets when battling to secure her 6-4 4-6 6-2 win over seventh seed Shuai Peng.
Monica Puig of Puerto Rico had an easier afternoon, cruising to a 6-3 6-1 victory over Mirjana Lucic-Baroni that pits her against Andrea Petkovic.
The German fourth seed - champion here in 2011 - played out the last match of the day alongside Vania King and needed just over an hour to record a 6-3 6-2 win over the American.