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Laurent Gillieron, AP Photo/Keystone
US Davis Cup tennis player John Isner reacts after he won against Swiss Davis Cup tennis player Roger Federer during a Davis Cup World Group first round second match between Switzerland and the US in the Forum Arena in Fribourg, Switzerland, Friday, Feb. 10, 2012.

FRIBOURG, Switzerland — John Isner shocked Roger Federer 4-6, 6-3, 7-6 (4), 6-2, giving the United States a 2-0 lead against Switzerland in their Davis Cup first-round series on Friday.

Isner's big serve backed and booming ground strokes challenged the Swiss star in long rallies on the indoor clay court.

The upset was preceded by a thrilling opening singles match, with Mardy Fish outlasting Stanislas Wawrinka 6-2, 4-6, 4-6, 6-1, 9-7.

The U.S. can eliminate Switzerland in doubles in the best-of-five series Saturday. Mike Bryan and teenager Ryan Harrison will face Federer and Wawrinka, the 2008 Beijing Olympics gold medalists.

Seven other first-round series in the top tier of Davis Cup were contested Friday. Croatia and Japan were tied 1-1; Serbia led Sweden 2-0; Austria led Russia 2-0 and Argentina led Germany 2-0. The other matchups are: Spain vs. Kazakhstan, Canada vs. France and Czech Republic vs. Italy.

A partisan crowd of 7,000 at the Fribourg Forum was stunned into silence by Federer's first loss in Davis Cup singles in eight years.

Federer had started in routine fashion, winning the first set without dropping serve. Isner broke Federer's serve in the sixth game of the second set, but failed to exert any pressure in the third.

Still, Federer couldn't take break point chances in the sixth and eighth games and the set drifted into a tiebreak.

Isner never trailed and clinched on his first set point with a subtle volley at the net that gave Federer no chance to retrieve.

The fourth set turned on the fifth game when Isner rallied from 0-40 down with three big serves and two blistering forehand winners.

Federer never recovered. Isner reeled off four straight games, ending the match by rifling a backhand winner crosscourt.