Svetlana Kuznetsova kept her hopes of playing at the WTA Tour Finals alive, but Carla Suarez Navarro's chances of reaching Singapore came to an end at the Kremlin Cup.
Kuznetsova is currently 10th in the race to Singapore, with Johanna Konta in the final qualifying spot, and needs to retain her title in Russia to play at the season-ending event.
And Kuznetsova remains in the hunt after clinically defeating Alize Cornet 6-4 7-5 to reach the quarter-finals in Moscow, the Russian impressively landing 81 per cent of first serves.
However, Suarez Navarro - who also had to win this tournament to play in Singapore - succumbed to a wrist injury when trailing 6-3 3-0 against Daria Gavrilova and retired hurt.
Russian duo Daria Kasatkina and Anastasia Pavlyuchenkova defeated Ekaterina Makarova and Jelena Jankovic in straight sets respectively.
Elina Svitolina, Timea Babos, Julia Goerges and Ana Konjuh were also among Wednesday's second-round winners.