Viktoria Hruncakova and Tereza Mihalikova then topped Townsend and Ashlyn Krueger 6-3, 3-6, 6-3 to get past Slovakia.
“We want to win so much, we gave everything”, said Hrunçakova. “I have no words.”
“The ranking is not important, but the heart and the team (is)”, said Mihalikova. “We beat the favorites and we are very happy.”
Earlier on Thursday, Japan beat Romania 2-1 as Shuko Aoyama and Eri Hozumi won the deciding doubles point 6-1, 7-5 over Elena Gabriela Ruse and Monica Niculescu.
Japan will face Italy in the quarterfinals.