American Alison Riske dumped out top seed Daria Gavrilova in the San Antonio Open quarter-finals.
Riske despatched Gavrilova, who is ranked 33rd in the world, 6-4 6-4 to set up a last-four meeting with Anna-Lena Friedsam.
Freidsam, who knocked out Naomi Broady in the first round, continued her good run of form, beating Ana Konjuh 6-4 4-6 6-2.
Misaki Doi is now the highest-seed left in the tournament after she beat Samantha Crawford 6-3 6-3 and she will meet Tsvetana Pironkova in the semi-finals after the Bulgarian demolished Donna Vekic 6-2 6-1.
Source: PA
