Lucky loser Ana Konjuh upset sixth seed Barbora Strycova 6-4 1-6 6-2 in the first round of the Kremlin Cup, while Anastasia Pavlyuchenkova edged past Katerina Siniakova.
After falling 4-1 down in the opening set Konjuh won five straight games to take lead in Moscow, though Strycova hit back by taking the second 6-1.
The 18-year-old Croatian was unperturbed and converted the first break point that came her way in the decider before Strycova failed to hold serve to remain in the match.
Konjuh will face qualifier Anna Blinkova in the second round after the Russia beat Anastasija Sevastova 6-4 1-6 7-6 (12-10).
Seventh seed and 2014 champion Pavlyuchenkova was forced to a third set by Czech qualifier Siniakova but triumphed 7-6 (7-2) 5-7 7-5 and Jelena Jankovic, who won the tournament in 2008, awaits her following a 6-3 6-3 win over Jelena Ostapenko.
Frenchwomen Alize Cornet and Kristina Mladenovic advanced following straight-set wins over Shelby Rogers and Anna Kalinskaya respectively, while Yulia Putintseva progressed after Lesia Tsurenko retired.
There were also wins for Daria Gavrilova, Ekaterina Makarova and Julia Gorges.