Updated

Hometown hero Novak Djokovic pulled out 0 of-five affair.

The high-flying Djokovic was scheduled to meet the oft-injured former Wimbledon runner-up Nalbandian on Day 1, but the weary star, who had been complaining about jet lag this week after capturing his first- ever U.S. Open title on Monday in New York before returning home to his beloved Serbia, cited some back pain on Friday and decided that playing was not an option.

The world No. 16 Troicki stepped in for Djokovic only to succumb to the 74th-ranked former top-five star Nalbandian, 6-4, 4-6, 6-2, 6-3, in 2 hours, 52 minutes at Belgrade Arena. Troicki fired 15 aces, but had his serve broken six times by the gritty Argentine. Nalbandian also recorded twice as many forehand winners (32-16) en route to victory.

Nalbandian is now 4-1 lifetime Troicki, who won the fifth and deciding rubber against France in last year's dramatic Davis Cup finale.

Djokovic's availability for Sunday's reverse singles is unknown at this point.

The reigning U.S. Open, Wimbledon and Australian Open titlist Djokovic, who is an amazing 64-2 this year and has earned more than $10.6 million in prize money, led the Serbs to their first-ever Davis Cup title last year when they beat the French in the final here in Djokovic's native Belgrade.

Friday's second singles bout will pit the hosts' Janko Tipsarevic against Argentine slugger Juan Martin del Potro, the 2009 U.S. Open champ.

Saturday's doubles match will pit a Serbian duo of Tipsarevic and Nenad Zimonjic versus an Argentine pairing of Juan Ignacio Chela and Juan Monaco, while Sunday's reverse singles currently call for Djokovic to tangle with del Potro and Tipsarevic to take on the former top-five star Nalbandian.

Argentina, captained by Tito Vazquez, is still seeking that elusive first-ever Davis Cup championship.

Serbia is part of the former Yugoslavia, which beat Argentina in Belgrade in their lone Davis Cup matchup way back in 1964.

The winner here will face the France-Spain victor in the 2011 Davis Cup final in December.