Elena Rybakina advanced to the last 16 at the Ostrava Open on Monday, but fellow former grand slam winner Victoria Azarenka exited at the first hurdle.
Rybakina, who has struggled for consistency since victory at Wimbledon earlier this year, came back from a set down to dispatch Madison Keys with a 5-7 6-3 6-3 win.
She could face eighth seed Jelena Ostapenko in the next round, but one name not in the draw will be Azarenka, who could not claw back victory against Ekaterina Alexandrova in a 6-4 4-6 2-6 defeat.
Alexandrova is in line to play either Emma Raducanu or Daria Kasatkina in the next stage.
Meanwhile, top seeds Iga Swiatek and Paula Badosa earned the identity of their opponents after receiving first-round byes.
Swiatek will play Ajla Tomljanovic, who progressed in straight sets against Zhang Shuai, as Badosa faces Petra Kvitova, who was made to work a little harder in three by Bernarda Pera.
At the Jasmin Open, third, fifth and seventh seeds Alize Cornet, Elise Mertens and Katerina Siniakova each advanced with respective straight-sets routs of Laura Pigossi, Jaqueline Cristian and Chloe Paquet – the latter retiring as she trailed 4-0 in the second set.
But eighth seed Magda Linette is out after letting an early lead slip against Lucrezia Stefanini, who celebrated a 2-6 6-4 6-4 victory.