Shelby Rogers claimed a place in the quarter-finals of the Internationaux de Strasbourg with a tense win over China's Wang Qiang.
The American, who benefited from Caroline Wozniack's withdrawal in the previous round, prevailed 6-4 6-4 on her sixth match point.
She was joined in the last eight by two Australians in Ashleigh Barty and seventh seed Daria Gavrilova, who will now play each other.
Barty saw off Camila Giorgi 6-3 6-0 with Gavrilova edging out Elizaveta Kulichkova 6-3 6-7 6-4. Frenchwoman Caroline Garcia beat Magda Linette of Poland 6-3 6-3.
Top seed Kiki Bertens continued her progress at the Versicherungs Cup in Nuremberg with a 7-5 6-2 success over Germany's Annika Beck.
The Dutchwoman struggled through a first set that saw seven breaks of serve but raised her level to win comfortably in the second.
Second seed Yulia Putintseva, of Kazakhstan, made comfortable progress as she overcame Belgium's Yanina Wickmayer 6-4 6-0.
Another Kazakh player, seventh seed Yaroslava Shvedova, beat German wildcard Tatjana Maria 6-2 6-4.
Carina Witthoeft won the all-German battle with Julia Goerges 6-1 7-5.
