Mandy Minella of Luxembourg and Lourdes Dominguez Lino of Spain fought back from a set down against seeded players to reach the Grand Prix SAR quarterfinals on Thursday.
Minella beat fourth-seeded Kaia Kanepi of Estonia 3-6, 6-4, 6-3, and Dominguez Lino downed ninth-seeded Tsvetana Pironkova of Bulgaria 1-6, 6-4, 6-3 in a match featuring seven breaks of serve for each player.
Kanepi had seven aces but double-faulted nine times, and Minella broke her three times.
Seventh-seeded Kristina Mladenovic of France advanced to the last eight by beating Yulia Putintseva of Kazakhstan 6-3, 6-3 and Spain's Silvia Soler-Espinosa joined her after thrashing Russia's Olga Puchkova 6-0, 6-3.
Later, defending champion Kiki Bertens took on Flavia Pennetta.