Top doubles duo Bob and Mike Bryan lost on Saturday for only the third time in 11 years of Davis Cup play as Brazil trimmed the US lead in their World Group first-round tie to 2-1.
Brazil's Bruno Soares and Marcelo Melo outlasted the American twins 7-6 (8/6), 6-7 (7/9), 6-4, 3-6, 6-3, the first time the Bryans had been pushed to a fifth set in Davis Cup play.
"To be able to come here and beat the No. 1 team in the world, it doesn't get much better than that," Soares said. "More importantly than that, we're still alive."
The Americans took the lead on Friday with straight-set singles triumphs by Sam Querrey and John Isner and they would advance if either can win in Sunday's reverse singles. Isner faces Thomaz Belucci and Querrey plays Thiago Alves.
The Bryans, who won their 13th Grand Slam title at the Australian Open, were denied on two break-point chances in the third game of the fifth set.
Mike Bryan was broken at love in the penultimate game of the match and Melo held serve to claim the match.
The Bryans squandered three set points in the first set before losing it and the Brazilians wasted four set points before dropping the second.