BOISE, Idaho -- The United States trails Serbia 2-1 in a Davis Cup quarterfinal after the top-ranked doubles team of Bob and Mike Bryan lost to Serbia's Nenad Zimonjic and Ilija Bozoljac 7-6 (5), 7-6 (1), 5-7, 4-6, 15-13 on Saturday.

Fans were on the edge of their seats throughout the 4-hour, 23-minute match. The Serbians had their share of fans, many of whom were waving the country's flag while urging on their team.

Zimonjic served three aces in the final game, closing out the victory with an ace on the second match point in the 28th game. It was a clutch performance by a multiple Grand Slam doubles champion.

"For sure, it's the biggest win in the Davis Cup doubles for me," said the 36-year-old Zimonjic, who was instrumental in Serbia's only Davis Cup victory in 2010. "We were playing very good.

"This was definitely a great, great performance and great match from me."

Bozoljac is a 27-year-old journeyman who ranks 335 in singles and 1,150 in doubles. Zimonjic and Bozoljac improved to 4-2 in Davis Cup doubles.

"Anybody who was supposed to play with Nenad was supposed to be the underdog against the Bryans," Bozoljac said. "We won and I just can't believe it happened.

"For me, it definitely means a lot because this is my best performance in Davis Cup so far. I knew if I give my 100 percent for one match I could play on a really high level."

The Bryans, who have a 20-4 Davis Cup doubles record together, have only played two five-set matches in Davis Cup competition and both took place this year. They were upset by Marcelo Melo and Bruno Soares of Brazil in the Davis Cup first round in February and by the Serbians in Boise.

"We have to tip our hats to those guys," Bob Bryan said. "Obviously, I thought they played well all day, 36 aces and they didn't give us much opportunity, especially in the fifth.

"We're obviously disappointed that we let the team down."

This marks the first time that the Bryans have lost consecutive Davis Cup doubles matches.

In other Davis Cup quarterfinals, Italy and Canada are tied 1-1, France and Argentina are also tied 1-1 and the Czech Republic has a 2-1 lead over Kazakhstan.

Zimonjic was the star of the opening two sets, appearing practically infallible with every shot he executed. But in the final set, the steadying force was the inexperienced Bozoljac, who boasts a strong serve, but often lacked experience in selecting the right doubles tactic.

"He's a guy we really haven't seen much of," Mike Bryan said of Bozoljac. "He served great all day. And he actually was the strong returner at the end, he didn't show any nerves and came up with the goods."

In the final set, the Serbians had two breakpoints on Bob Bryan's serve in the ninth game, but the Americans were able to rally to save that service game.

The Serbians again had two breakpoints, this time on Mike Bryan's serve in the 27th game, and converted on a Mike Bryan error on the second break opportunity.

In the final game, the Bryans had their only two opportunities to break the Serbians' serve in the final set, but Zimonjic saved them with a service winner and an ace.

Sunday's reverse singles matches will start with world No. 1 Novak Djokovic playing 20th-ranked Sam Querrey. The final match will be 44th-ranked Viktor Troicki of Serbia against 23rd-ranked John Isner.

"Nothing changes," said U.S. captain Jim Courier. "We know where we stand. We know what we have to do.

• Read more articles by SANDRA HARWITT

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