Mike and Bob Bryan won Saturday's doubles for the United States to trim Spain's lead in their Davis Cup semifinal to 2-1.
The twins were stretched by Marcel Granollers and Marc Lopez in a 6-3, 3-6, 7-5, 7-5 victory in which Granollers appeared hampered by a left calf injury picked up in the second set.
Granollers stayed in the match but Spain lost momentum and mobility as the Bryans kept alive the visitors' chances of reaching November's final in front of a near capacity 15,000 spectators at the purpose-built venue in the Asturian coastal city.
David Ferrer can clinch Spain's fourth trip to the final in five years on Sunday when he faces John Isner in reverse singles, with the fifth-ranked Spaniard 15-0 on clay in the competition.
"It's a shame because we felt really good today... It happened to me in the U.S. one week ago, it's tough "
Spaniard Marc Lopez
The defending champions are 37-0 after opening the semifinal with a sweep of the opening singles points.
The U.S. has only once recovered from a 0-2 deficit - in 1934 - but its record improves when down 1-2, having done it five times with the last being in 2000.
Mike Bryan stumbled chasing down a drop shot to miss out on the first match point, but Lopez provided the U.S. with it on the second opportunity as he double-faulted.
"It's a shame because we felt really good today,'' said Lopez before alluding to his own calf problem that forced him to retire from the U.S. Open doubles semifinal.
"It happened to me in the U.S. one week ago, it's tough.''
Should Isner beat the fifth-ranked Ferrer, Sam Querrey and Nicolas Almagro are scheduled to play for the final singles point.
Almagro edged Isner in a five-set thriller on Friday to bring his and Ferrer's record on clay in the competition to a combined 23-1.