Julia Goerges advanced to the quarterfinals of the Moscow River Cup with a 6-2 7-6 (2) victory over Russia's Natalia Vikhlyantseva.
The German top seed is the strong favourite to add another Russian trophy to her collection, after winning the Kremlin Cup, also held in Moscow, in 2017.
In the last of the first round games, seventh seed Alize Cornet, champion at the Swiss Open this month, was defeated by Laura Siegemund 4-6 6-2 6-3 while third seed Anastasija Sevastova beat Pauline Parmentier 6-2 3-6 6-4.
Elsewhere, lucky loser Olga Danilovic continued her impressive run by defeating eighth seed Kaia Kanepi 7-6 (3) 7-5. Kanepi will now face Goerges in the last eight.
Valentyna Ivakhnenko also beat Vavara Flink to set up a quarterfinal against Anastasia Potapova, who advanced with a 6-4 6-4 win over Kristyna Pliskova.