* Nestor and Pospisil edge five-set marathon
* Canada 2-1 up in Davis Cup semi-final
* Serbia look to Djokovic to lead fightback (adds quotes, detail)
BELGRADE, Sept 14 (Reuters) - Daniel Nestor and Vasek Pospisil subdued Nenad Zimonjic and Ilija Bozoljac 6-7(6) 6-4 3-6 7-6 (5) 10-8 in a rip-roaring doubles on Saturday to give Canada a 2-1 lead against 2010 winners Serbia in their Davis Cup semi-final.
Games went with serve in the final set until the tiring Zimonjic sliced a backhand into the net on his serve and Pospisil held in the final game of the four-hour, 20-minute contest.
Serbia's world number one Novak Djokovic takes on 11th-ranked Milos Raonic in Sunday's opening reverse singles in the first meeting between the two players before Janko Tipsarevic plays Pospisil in the tie's final rubber.
Zimonjic and Bozoljac saved three set points to nose ahead in front of 8,000 vociferous fans in Belgrade's Kombank Arena, including several hundred flag-waving Canadian supporters.
Nestor, who won one French Open and two Wimbledon titles with Zimonjic before they split in 2010, engineered a break of his former partner's serve in the second set, which put Canada on level terms.
A delicious backhand down the middle from Bozoljac broke Nestor's serve in the sixth game of the third set, allowing Serbia to regain control of the match before Pospisil redressed the balance when he sealed the fourth set tie-break with an ace.
Bozoljac saved one match point on Pospisil's serve but was powerless to stop the second as the 22-year-old wrapped up the slugfest with a stinging forehand down the line.
Nestor was full of gratitude for Canada's travelling support. "They were amazing and we really appreciate the time and resources they sacrificed to come here for us," the 41-year old Belgrade-born doubles specialist told a news conference.
"We've never had support like this away from home in the Davis Cup and we are delighted to have won a high-quality match against the home team in a tough environment.
"Our own celebrations at the end of it were very emotional because we are having a great year."
Bozoljac said: "We played in fits and starts.
"All four of us on the court were very aggressive and served well, but our undoing was that we couldn't string more than a couple of good returns together at crunch time.
"We missed too many chances to come out on top but are still optimistic that Novak and Janko can turn it around."
(Editing by Justin Palmer and Stephen Wood)