Fribourg, Switzerland, 12 February 2012 | AFP

The United States reached the Davis Cup quarter-finals on Saturday when the doubles pairing of Mike Bryan and Mardy Fish gave them an unbeatable 3-0 lead over hosts Switzerland.

The Americans defeated Olympic champions Roger Federer and Stanislas Wawrinka 4-6 6-3 6-3 6-3 to secure the winning point.

In Friday’s opening two rubbers, Fish defeated Wawrinka in five sets and John Isner upset Federer in four.

Defending champions Spain reached the Davis Cup quarter-finals for a sixth successive year when they secured an unassailable 3-0 lead over visitors Kazakhstan.

Marcel Granollers and Marc Lopez defeated Evgeny Korolev and Yuriy Schukin 6-2 6-3 6-1 in the doubles to put Spain, playing without Rafael Nadal, into a last eight clash against either Austria or Russia.

In Friday’s opening singles, Juan Carlos Ferrero had beaten Mikhail Kukushkin 6-1 4-6 7-6 (7-2) 4-6 6-4 whole Nicolas Almagro saw off Andrey Golubev 6-3 4-6 6-1 6-1.

In other World Group results:

Czech Republic leads Italy 3-0
Serbia is 2-1 against Sweden
Croatia leads Japan 2-1
Argentina leads Germany 3-0
Austria leads Russia 2-1
Canada and France are tied 1-1

Asia/Oceania Zone 1
Australia leads China 3-0
Korea leads Chinese Taipei 3-0
Uzbekistan leads New Zealand 3-0
Indian bye