Top seed Sloane Stephens crashed out of the Nuremberg Cup on Wednesday, while defending Internationaux de Strasbourg champion Sam Stosur again got the better of Daria Gavrilova.
Stephens' first-round clash with Yulia Putintseva had been halted by bad light at 3-3 in the third set on Tuesday night, with play commencing the next day.
And the US Open champion, who had been struggling, could not arrest her opponent's momentum as Putintseva sealed a shock 5-7 6-4 7-6 (7-3) triumph.
Putintseva had been set to face Alison Riske in the last-16 later in the day, but rain this time interrupted the schedule, limiting the tennis played in Germany.
Sixth seed Sorana Cirstea still found time to defeat Madison Brengle, while Heather Watson was dumped out to teenager Fanny Stollar 6-3 6-3 and Kirsten Flipkens overcame Nadia Podoroska 7-6 (8-6) 6-2.
In Strasbourg, a repeat of the 2017 final brought the same result as Stosur downed Gavrilova.
The all-Australian tie ended 6-3 6-4 in Stosur's favour after she fought back from 4-1 down in the second set, winning five games in succession to remain on course for consecutive titles.
The 34-year-old could well be set for a final meeting with top seed Ashleigh Barty, who advanced to the last eight by seeing off Pauline Parmentier 6-1 6-4.
Fellow seeds Anastasia Pavlyuchenkova and Su-Wei Hsieh are also through to the quarter-finals.