Querrey took out Thomaz Bellucci 6-3, 6-4, 6-4 in an efficient 99 minutes and Isner followed with a 6-3, 7-6 (7-4), 6-3 decision over Thiago Alves.
The United States sends out world No. 1 doubles team Mike and Bob Bryan with a chance to wrap up the best-of-five series Saturday. The Brazilians counter with the team of Marcelo Melo and Bruno Soares, both Top 20 doubles players.
Isner is to play Bellucci in Sunday's first singles match with the final series match scheduled to be Querrey versus Alves.
The winner of the Brazil-United States pairing draws either Serbia or Belgium in the quarterfinals. Serbia is up 2-0 in that series.
Querrey had 43 winners, including 15 aces, against 30 unforced errors while winning an amazing 83 percent of the points on serve. He had just one break in each set but that was all he needed as he didn't face a break point.
Isner had 32 aces and saved the three break points he faced. Isner has 72 winners and won 73 percent of the points on serve.