Pablo Carreno Busta was knocked out of the Kremlin Cup in the second round by Daniil Medvedev 6-3, 6-3 on Thursday.
The Russian broke 11th-ranked Carreno Busta twice in each set.
Medvedev's win sets up a quarterfinal against Bosnian qualifier Mirza Basic.
Earlier, Russia's Daria Kasatkina became the first player to book a place in the semifinals of the women's draw, beating Aliaksandra Sasnovich of Belarus 6-4, 6-3.
Standing between Kasatkina and her second career final is Irina-Camelia Begu of Romania, who prevailed against qualifier Vera Lapko of Belarus 6-3, 4-6, 7-5 in their quarterfinal.
