The U.S. took a winning 3-0 lead over Spain in their Davis Cup world group quarter-final tie on Saturday when Bob and Mike Bryan beat Feliciano Lopez and Fernando Verdasco 7-5, 6-3, 3-6, 7-6.
The doubles pairing wrapped up the tie a day early to move into a September 21-23 semi-final in Sweden.
Andy Roddick and James Blake, who won their singles on Friday, were first to cheer their team mates after the two-hour 38-minute victory.
The visitors saved a match point in the 10th game of the fourth set with an ace from Lopez but as the set went into a tie-breaker, the Americans, cheered by a 14,500-strong home crowd, raced to 4-1.
A Bryan return which skipped the net cord yielded two more match points with the hosts advancing on the second.
"We had to play our best, they were tough," Bob Bryan told reporters. "We stayed positive when it went to a fourth set."
Mike Bryan added: "They were hitting aces on every big point and I couldn't read their serves. We had to hang in there."
The victory was the 11th in 12 Davis Cup appearances for the 28-year-old pair from California who have 36 titles to their credit and have been finalists in 11 of the last 16 Grand Slams.
The U.S. 31-times Davis Cup champions, improved to 13-1 in quarter-finals played at home. Spain were without world number two Rafael Nadal, resting a foot injury.