Russia's Konstantin Kravchuk defeated Evgeny Korolev of Kazakhstan in straight sets at the Kremlin Cup on Tuesday.
Kravchuk, ranked 297 in the world, dominated the encounter, racking up 16 aces against Korolev's two to secure a 6-4, 6-3 win in a battle of two qualifiers.
The next opponent of the 27-year-old Russian will be eighth seed Tatsuma Ito of Japan.
Earlier in the women's draw, Tsvetana Pironkova upset U.S. No. 2 Varvara Lepchenko 6-0, 7-6(3) in the first round.