Kostyuk, Friedsam into last-eight in Texas WTA event

She will meet Germany's Anna-Lena Friedsam for a spot in the semi-finals at the inaugural edition of the hard-court ATX Open tournament in Austin, Texas.

The 108th-ranked Friedsam edged out Erika Andreeva 7-5 6-7 (2-7) 7-6 (8-6). 

The other singles matches scheduled for later Thursday include No.4 seed Danielle Collins taking on Caty McNally, and CoCo Vandeweghe against Anna Kalinskaya.

The other quarter-final matchups already decided will pitch fifth seed Sloane Stephens against Varvara Gracheva, and Katie Volynets against Peyton Stearns.