Italy kept their Fed Cup title defence on track Sunday, downing the United States to join Australia and Germany in the semi-finals of the women's tennis competition.
Gemany's Angelique Kerber celebrates her victory against Slovakia's Dominika Cibulkova during the Fed Cup match in Bratislava on February 9, 2014
Karin Knapp claimed the decisive third point for Italy, giving them an unbeatable 3-0 lead with a 6-3, 7-5 victory over American Alison Riske.
The holders won't know their opponents for the April 19-20 semi-finals until Monday, after rain in Seville forced decisive matches in Spain's clash with the Czech Republic to be pushed back with the hosts holding a 1-0 lead.
Both Italy and the United States were without their top players for the tie on an indoor hard court in Cleveland, Ohio.
Italy, seeking a fifth Fed Cup in nine years, were without Sara Errani and Flavia Pennetta, while the United States were without injured stars Serena Williams and Sloane Stephens.
But Knapp, ranked 40th in the world, came through with two victories. She opened the tie with a 6-3, 3-6, 6-1 win over Christina McHale on Saturday, when Camila Giorgi crushed US teen Madison Keys 6-2, 6-1.
In the meaningless doubles match, Keys and Lauren Davis teamed up to beat Nastassja Burnett and Alice Matteucci 6-2, 6-3 and prevent the whitewash, giving Italy a final 3-1 triumph.
US captain Mary Joe Fernandez opted to substitute Riske for Keys in Sunday's reverse singles, hoping her more aggressive style would prove troublesome for the Italian.
Instead, Knapp broke Riske seven times, and while the Italian's nerves got the better of her in her first two chances to serve for the match, she finished it off in style with a love game punctuated by a service winner on her first match point.
"I got a little bit nervous," Knapp admitted. "I got a little bit of emotion. At the end, the last game, I served again better. I think this was the key."
In Hobart, Australia ensured their place in the next round for the first time in 21 years with a crushing Samantha Stosur-inspired 4-0 defeat of Russia.
The 2011 US Open champion added to her Saturday singles win when seeing off FedCup newcomer Victoria Kan 6-2, 6-3 in Sunday's opening rubber to secure an unassailable 3-0 lead.
Ashleigh Barty and Casey Dellacqua sealed a 4-0 clean sweep over the Russians with an emphatic 6-1, 6-3 doubles win over Irina Khromacheva and Valeria Solovyeva.
"We're still in it, so we have a chance to win it," Stosur said of Australia's prospects of claiming the title for the first time since 1974.
First though they will have to overcome Germany, waiting for them in the semis.
The Germans, who were last crowned champions in 1992, qualified 3-1 after Angelique Kerber defeated Slovakia's Australian Open runner-up Dominika Cibulkova 6-3, 7-6 (7/5) in the first of the reverse singles in Bratislava.
Kerber had already beaten Daniela Hantuchova 7-6 (11/9), 6-1 in the second of Saturday's two singles, after Andrea Petkovic had saved a match point en route to a 1-6, 7-6 (9/7), 6-2 win over Cibulkova.
"It was tough, so I was just trying to play point-by-point. I think I played well, I moved well, I mixed it up well, sometimes aggressive, sometimes defensive, and I’m so happy that we’re now through," Kerber said.
Slovakia picked up their point courtesy of Jana Cepelova and Magdalena Rybarikova's 4-6, 6-3, 10-7 doubles win over Julia Goerges and Anna-Lena Groenefeld.
This is the first time Germany have graced the last four since 1995.