Boise, Idaho - Serbia took a major step towards reaching the semi-finals by outlasting hosts USA in a marathon five-set victory in Saturday's doubles competition of their Davis Cup tie.
Ilija Bozoljac and Nenad Zimonjic shocked the top-ranked doubles team of Bob and Mike Bryan 7-6 (7/5), 7-6 (7/1), 5-7, 4-6, 15-13 to give Serbia a 2-1 lead in their best-of-five tie heading into a pair of Sunday's reverse singles matches.
World No 1 and reigning Aussie Open champ Novak Djokovic can send Serbia into the semis with a win Sunday over American Sam Querrey, who is ranked 20th in the world.
The 25-year-old Djokovic has captured two ATP Tour titles in 2013, winning 19 singles matches and losing just two. Earlier this year he claimed his sixth Grand Slam title by beating Andy Murray in the final of the Australian Open.
Querrey has a 13-7 record this year with no titles.
Djokovic has won five of six careers meetings against Querrey, including a 6-0, 7-6 (8/6) win last month in Indian Wells, California.
Serbia defeated the 32-time titlist Americans 3-2 in Belgrade in an opening-round tie three years ago in their lone previous Davis Cup encounter.
In a match that lasted four hours, 23 minutes on Saturday, the Serb duo jumped out to a two set lead before the Bryan brothers battled back.
In the other reverse singles match Sunday, Viktor Troicki will take on American world No 23 John Isner.
The Serbs are captained by Bogdan Obradovic while Jim Courier is advising the hosts.
The winner of the US and Serbia quarter-final tie will meet either Canada or Italy in September.