Andrea Petkovic and Angelique Kerber both won Sunday for Germany to advance to the Fed Cup semifinals at Australia's expense with an insurmountable 3-1 lead in their World Group tie.
Petkovic defeated Jarmila Gajdosova 6-3, 3-6, 8-6 in just under two hours to set up a semifinal against Russia, which defeated Poland in Krakow.
Gajdosova fired 10 aces in the match and broke twice in the decisive set, only for Petkovic to hold her nerve and fight back.
"I'm so relieved we managed it," the world No. 12 said. "I was getting tired toward the end and was only thinking from point to point."
Earlier, Kerber needed 1 hour, 27 minutes to beat Australian No. 1 Samantha Stosur 6-2, 6-4, atoning for her loss to Gajdosova in Saturday's opening rubber.
"Today I had to beat both myself and Sam," Kerber said. "I couldn't sleep last night, I was so disappointed. I wanted to show everyone today that I can be better."
Stosur had played the second longest set in World Group history on Saturday in her 6-4, 3-6, 12-10 loss to Petkovic that left the tie even at 1-1.
Only pride was at stake in the doubles match featuring Julia Goerges and Sabine Lisicki against Casey Dellacqua and Stosur scheduled for later Sunday.
Germany lost last year's final to the Czech Republic.
