World No.3 Roger Federer slumped to a shock 4-6 6-3 7-6 (7-4) 6-2 defeat to John Isner on Friday as the United States opened up a 2-0 Davis Cup first round lead.

Federer, playing a first round tie for the first time in eight years, saw his 15-match winning streak in the competition ended by the giant Isner on the indoor clay courts at Fribourg.

Isner secured victory with three return winners as the 32-time Davis Cup champions America moved close to a quarter-final spot.

“The way I played today is the way I need to play in all my matches,” said Isner, who paid tribute to captain Jim Courier.

“I owe it to Jim Courier – he was on at me to hit all my shots. It’s the win of my life.”

Earlier, Mardy Fish defeated Stanislas Wawrinka 6-2 4-6 4-6 6-1 9-7 in the opening rubber.

Fish fought back after wasting a match point chance at 5-4 in the decider, and clinched victory six games later with a cushioned, crosscourt volley winner at the net.

An 86-minute final set saw wild shifts in momentum and emotion, before the eighth-ranked American improved his record to 3-0 against the 28th-ranked Wawrinka.

The winners of the tie will face either France or Canada in April for a place in the semi-finals.