BELGRADE, Serbia — Bob Bryan and John Isner defeated Nenad Zimonjic and Janko Tipsarevic 7-6 (8), 5-7, 7-6 (8), 6-3 in doubles to keep the United States alive in the Davis Cup first round, cutting Serbia's lead to 2-1.
Isner was a last-minute replacement for Bryan's twin Mike, who was sidelined with food poisoning. The Bryans are the world's top doubles team.
Isner, who made his Davis Cup debut on Friday, will try to even the tie on Sunday when he plays second-ranked Novak Djokovic in the first reverse singles on an indoor clay court at Belgrade Arena. Sam Querrey is set to play the final singles match against Viktor Troicki.
"I'm a bit tired now, but it won't affect me too much tomorrow against Djokovic," said Isner, No. 20 in the world rankings. "I really have nothing to lose as he's the No. 2 player and not me."
On Friday, Isner lost the opener to Troicki while Djokovic beat Querrey.
The U.S. has only won once after falling behind 2-0 in the Davis Cup, against Australia in 1934.
Serbia is trying to pass the World Group first round for the first time.
This was the first time that Bob Bryan played doubles in the Davis Cup without his brother. The two are 9-0 in Davis Cup matches on the road and have 16 doubles wins together in the competition, the most of any U.S. doubles team. Mike Bryan got sick after eating a hotel room service dinner on Friday.
"John is a good doubles player and I enjoyed playing behind his big serve," Bob Bryan said. "It definitely was a new experience for me, we pulled a couple of amazing tiebreakers."
The Serb duo wasted five set points in the first-set tiebreaker, with the Americans converting their second. In the third, a set point for the Serbs was annulled by the umpire and the point was given to the Americans after Zimonjic called an Isner service out during play even though the ball was in.
"The referee was right, and I made a mistake," said Zimonjic, the world's top ranked doubles player. "All the credit to the Americans, who served real well and handled the pressure perfectly."