But it should be able to rely on the Bryan brothers to keep alive chances of reaching the Davis Cup final.
David Ferrer and Nicolas Almagro were winners over Sam Querrey and John Isner as Spain swept singles play Friday to put it on the verge of a fourth Davis Cup final in five years.
The hosts have their first opportunity to clinch the series come Saturday's doubles, when Bob and Mike Bryan can at least look to keep the series alive to Sunday's reverse singles for the Americans, whose one and only comeback from a 0-2 deficit was 88 years ago.
"Bob and Mike are extremely confident and extremely prepared, and I'm sure the Spanish team feels the same," US captain Jim Courier said of his doubles players, who are fresh off a U.S. Open doubles victory that was their record 12th Grand Slam doubles title.
"A lot of things can change momentum wise on Saturday and Bob and Mike are part of making that happen."
The Bryans are 4-0 when their singles teammates have been swept on opening day and are 5-0 against Spain, which will be counting on Marcel Granollers and Marc Lopez to secure another trip to the final.
"After the effort the Americans showed today, we know that final point won't be easy," Spain captain Alex Corretja said, whose nation is 37-0 when sweeping opening singles since the start of World Group play. "They've shown they've come here to give everything."
Though they didn't make it look as easy as Rafael Nadal does, Ferrer and Almagro showed dogged determination to improve their near-perfect Davis Cup clay court records to 23-1.
Ferrer overcame a sluggish start to put the hosts ahead in the best-of-five series with a 4-6, 6-2, 6-2, 6-4 win over Querrey before Almagro overcame Isner's constant fight backs in a 6-4, 4-6, 6-4, 3-6, 7-5 victory.
While Querrey wasted nine break opportunities in the fourth set of his match to lose, Isner took advantage of his lone one in the fourth set of his match to stretch it to a fifth and deciding frame.
As the light quickly faded, neither player relented on serve as Isner fired 25 aces, including to save a 16th break point before three of his 124 errors on the day undid him in the final game.
Isner netted on consecutive points to give Almagro his last match point, which the plucky Spaniard converted when Isner's forehand sailed long.
"Those were pretty bad errors, they were simple shots especially from volleys. I should have made all of them," Isner said after his 4 hour, 16 minute match. "Maybe fatigue played a part, but I did such a good job of hanging in there the whole fourth set and I sort of gave it away in that last set."
Ferrer, who played in the US Open semifinals on Sunday, started well with a break but eventually surrendered his only two service games of the match for the defending champions to trail after the first set.
Querrey, returning to Davis Cup play for the first time since 2010, failed to maintain his early rhythm and was broken six times by the fifth-ranked Ferrer, whose ability to hold his serve secured a hard-fought victory by saving nine break points in the fourth set to hold off a late charge from his opponent.
"It's never easy to adapt from hard court to clay, and with only three to four days even less," said Ferrer, who is 15-0 on clay in the competition. "I didn't feel too bad but I didn't play perfect tennis either."
Querrey had taken a set off Nadal in his Davis Cup debut four years ago but couldn't hold his early momentum nor secure a late break at the purpose-built Hermanos Castros Park venue, where the wind gusted off the Bay of Biscay and neither player served particularly well to combine for 12 double faults.
"On a couple of them I should have been more aggressive but he played good points," said the 26th-ranked Querrey, who hit 70 unforced errors while failing to convert 12 break chances. "I feel if I get one of those breaks it could be a different game."
Courier was confident the Bryans could provide his singles players with a lift with Isner set to play Ferrer should the Americans win Saturday, with Almagro facing Querrey after that.
The winner plays either Argentina or the Czech Republic in November's final. Sapa-AP