Andy Roddick had given the Americans the lead with a 6-2, 4-6, 6-3, 6-4 victory over Nicolas Massu. It took Capdeville more than 4 hours to even the best-of-five series with a 6-7 (5-7), 6-7 (2-7), 7-6 (7-3), 7-6 (7-5), 6-4 decision over John Isner.
Capdeville recorded the lone break of the match in the ninth game of the fifth set and then served out. Between them, Isner and Capdeville were 1-of-19 on break-point chances as they won 72 percent of the points on serve.
Isner had 38 aces and 114 winners in the match but also amassed 96 unforced errors.
Roddick's 2-hour, 49-minute battle was routine in comparison. He dropped serve just once and had 75 winners against 40 unforced errors.
The United States will send out the world No. 1 doubles team of twin brothers Bob and Mike Bryan Saturday against Chileans Jorge Aguilar and Massu.
Roddick goes against Capdeville in the first of Sunday's two reverse singles matches with Isner and Massu to meet in the final match.
Chile and the United States are playing for a Davis Cup quarterfinals slot against the winner of a series between Belgium and Spain. Spain is ahead 2-0 in that series.