It looked like Sock was still deflated by Friday's defeat when Australia raced to a 4-1 lead in the first set and Peers slammed down an ace to seal it in 27 minutes.
Jordan Thompson and Nick Kyrgios gave Australia a 2-0 lead over the United States in their Davis Cup tennis quarter-final tie with hard-fought singles victories here on Friday.
The two countries have 60 Davis Cup titles between them but Australia have not won since they bagged their 28th crown in 2003, while the U.S. snared their 32nd a decade ago.
"There is no greater honour than to play for the green and gold and leave everything out there in Davis Cup", said Thompson, who is scheduled to play the fifth rubber on Sunday against Isner.
USA team captain Jim Courier, left, talks to his players during the doubles match between Australia's Sam Groth and John Peers, and Jack Sock and Steve Johnson of the U.S.at the Davis Cup World Group Quarterfinal in Brisba.
"I'm only human. I'm not going to change in that department", Kyrgios said.
"We knew it was going to be tough today", said Kyrgios.
Kyrgios took his Davis Cup singles win-loss record to 6-3 with his 7-5, 7-6 (7-5), 7-6 (7-5) win over Isner, who saved four break points in the third set and a match point at 5-6 in the third set.
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Jordan Thompson caused an upset as Australia came out on top on the first day of their Davis Cup quarter-final against the United States.
Another barrage of huge serves saw Kyrgios steal a march in the second set tiebreak and after running the big American all over the court, he grabbed the set with a cheeky drop-shot.
The victor of the quarterfinal will play Italy or Belgium in September. A late break point allowed him to win the opening set, and the following two sets would go into tiebreakers, where Kyrgios was just a hair better than Isner, winning both breakers by a score of 7-5.
"There could be worse ways to start", Thompson said. "We're certainly not happy with the score but we're professionals and we'll be ready to play tomorrow".
"(I tried to) play within myself, not try to hit it too big, because that is not really my style".
"I've been playing great tennis".
Thompsons victory continues the 22-year-olds undefeated run for Australia in Davis Cup after he won both his singles rubbers on debut against Czech Republic at Kooyong in February in straight sets.