Feb 3 (OPTA) - Results from the WTA Premier, St Petersburg Women's Singles matches on Friday .. Quarter-final .. 8-Daria Kasatkina (RUS) beat 1-Caroline Wozniacki (DEN) 7-6(2) 6-3 4-Kristina Mladenovic beat Katerina Siniakova (CZE) 6-4 6-3 (FRA) 5-Julia Goerges (GER) beat Elena Rybakina (RUS) 6-3 6-3 Petra Kvitova (CZE) beat 2-Jelena Ostapenko (LAT) 6-0 6-2