Switzerland's Roger Federer and Lorenzo Manta have defeated the United States' Jan-Michael Gambill and Justin Gimbelstob, 6-4, 6-2, 7-5, at Saturday's Davis Cup doubles match in Basel.
The Swiss win puts the US on the brink of elimination from the tournament.
The Americans must win both singles on Sunday, in the best-of-five opening round tie, in order to stay alive.
Federer and Manta played well as a team on Saturday, while the Americans were consistently unable to return serve and volleyed erratically.
Federer told swissinfo, "We played really well today, very solid, we never lost our serves. It was great playing with Lorenzo Manta, who is on an eight-win streak in Davis Cup doubles."
Swiss captain, Jakob Hlasek, was also very proud of his team's performance. "I think from the first moment to the last, they played exceptionally well."
Switzerland broke in the third game of the first set when Gambill hit a volley long. Gambill and Gimbelstob never managed to break the Swiss in their three sets and with only one breakpoint in their first two sets, they failed to capitalise.
In the second set, the Swiss began to rattle the American pair when they questioned a few calls.
Switzerland broke in the fifth game of the second set after Gambill hit a volley wide. They broke again in the seventh, when Gambill hit a volley long.
The Swiss waited until the 11th game to break the US in the final set, converting on their third breakpoint of the game when Gambill netted a forehand volley with Federer serving out to win 7-5.
The 19-year-old from Basel said he believes his hometown advantage has helped him towards victory. "I've always been dreaming about playing in the Davis Cup, playing at home, and it's really special to me," he told swissinfo.
Following Saturday's defeat against Switzerland, there may be even more bad news for the Americans on Sunday. Todd Martin, who lost to Federer in Friday's singles match, won't know until Sunday if he'll be able to play the fifth singles match for the United States.
Martin picked up a back injury in the fourth set of his match against Federer on Friday. The 30-year-old Martin is slated to go up against Switzerland's Michel Kratochvil in what could be the deciding match between the Swiss and the Americans.
If Martin can't play Kratochvil, the US Davis Cup captain, Patrick McEnroe, said he would use 18-year-old Andy Roddick.
Meanwhile, Federer said he confident about going up against Gambill on Sunday. "I've played him three times and I've beaten him three times," Federer told swissinfo, "and to play at home in Basel against him will definitely be an advantage".
by Samantha Tonkin and Anna Nelson