The unheralded Czech Republic have upset the United States to reach the Billie Jean King Cup semi-finals for the first time in four years.
The Czechs will meet Switzerland on Saturday in Glasgow after the Swiss beat Canada 2-1.
Fellow group winners Australia and Britain meet in the other semi-final.
No.7-ranked Coco Gauff and No.14 Danielle Collins were expected to roll over the Czechs in their singles but neither could win a set.
Gauff won all three previous matches against Katerina Siniakova but fell 7-6 (7-1) 6-1.
The young American made 39 unforced errors in her fifth straight singles defeat.
Collins was overwhelmed by Marketa Vondrousova 6-3 6-3. The Czech won eight games in a row from 3-1 down.
Vondrousova only recently returned to the tour after six months out following wrist surgery.
In her second minor comeback tournament last week in England, she won the singles and doubles and carried the form to Glasgow.
Switzerland, the 2021 runner-up, took an unassailable lead over Canada after Viktorija Golubic rallied to beat Bianca Andreescu 2-6 6-3 6-4 and Belinda Bencic beat Leylah Fernandez 6-0 7-5.
Golubic stood in for Jil Teichmann, who was on court for four hours on Wednesday. The switch was inspired as Golubic refocused in the second set, broke early, and held her ground.
Fernandez beat Bencic in the tournament two years ago but Bencic won their most recent contest last month in Guadalajara and carried it on.