Jack Sock and John Isner won the opening singles on Friday to give the United States a commanding 2-0 lead over Switzerland in their Davis Cup World Group first-round tie.
World number 20 Sock got the United States off to a fast start, breezing past Swiss Marco Chiudinelli 6-4, 6-3, 6-1.
The 24-year-old American, who cracked the top 20 for the first time in his career with a second-consecutive runner-up effort last month in Auckland, needed one hour, 58 minutes to dispatch his 146th-ranked rival.
Sock fired 12 aces with only one double fault and lost only one of 33 points on his second serve. He also denied Chiudinelli on all four break points he faced, all in the final set.
Isner, ranked 23rd, had to work a little harder for a 4-6, 6-2, 6-2, 7-6 (7/1) victory over Henri Laaksonen, ranked 127th in the world.
"There were a few extra nerves I think playing Davis Cup," Sock said. "When you're playing for your country, being part of a team, maybe at a normal event, normal tournament, you come out swinging a little bit more.
"I think I was a little hesitant at the beginning, maybe too conservative playing when obviously my game is to kind of play big and hit forehands and be aggressive.
"But after getting the break (to win the first set) it loosened me up a little bit and I was able to play a little bit bigger," Sock added. "That's how I like to see matches go. I love playing in front of a home crowd. I love playing at home, especially Davis Cup. I love being on the team."
The Americans can wrap up the best-of-five match contest in Birmingham, Alabama, with a victory in Saturday's doubles, when Steve Johnson and Sam Querrey will play the Swiss duo of Antoine Bellier and Adrien Bossel.
Reverse singles are set for Sunday if the Swiss can extend the match.
The US squad is 3-1 against the Swiss in Davis Cup play, losing only in 2001 when Roger Federer won two singles and played a triumphant doubles match.
Switzerland lifted the trophy in 2014, but are without their biggest stars in Federer and Stan Wawrinka.
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