John Isner spoiled a rare Davis Cup appearance by Roger Federer by stunning the Swiss 4-6 6-3 7-6 6-2 to give United States a 2-0 lead in their World Group first-round tie in Fribourg Friday.
Isner, involved in a record 11-hour five-minute marathon victory over Frenchman Nicolas Mahut at Wimbledon in 2010, ended world number three Federer's 15-match unbeaten run in Davis Cup singles.
"It's one of the greatest wins of my life, no that's wrong, it's the greatest win of my life," Isner said in a courtside interview.
"I really owe a lot to captain Jim Courier. He was on at me in practice all week, told me to do all the right things, every single practice, hit all the right shots.
"I'm going to make mistakes, that's how I play, but the way I played today, that's how I need to play in all my matches."
Mardy Fish had earlier edged Stanislas Wawrinka 6-2 4-6 4-6 6-1 9-7 as Switzerland's bid to reach the quarter-finals for the first time since 2004 got off to the worst possible start against the team that beat them in the 1992 final.
Big-serving Isner, ranked 17th in the world, lost his two previous meetings with former world number one Federer, both on hardcourts, but he silenced the home crowd with an efficient performance on the clay at the Forum Fribourg.
"The mission was to go out there and not allow an artist a canvas to work with," Courier said of Isner's victory.
The winners of the tie will play away against Canada or France in the quarter-finals.
(Writing by Iain Rogers in Madrid, editing by Tony Jimenez)