Mike and Bob Bryan won Saturday's doubles match for the United States to trim Spain's lead in their Davis Cup semifinal to 2-1.
The twin brothers 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.
David Ferrer can clinch Spain's fourth trip to the final in five years Sunday when he faces John Isner in reverse singles.
The defending champions are 37-0 after opening the best-of-five World Group series 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 prior.