11/13/2013 09:50 EST | Updated 01/23/2014 06:58 EST

Serbian player Janko Tipsarevic doubtful for Davis Cup final against Czech Republic

A chronic heel injury has Janko Tipsarevic in doubt for Serbia in the Davis Cup final against defending champion Czech Republic, piling the pressure on Novak Djokovic to deliver a home-court victory this weekend.

Tipsarevic said on Wednesday he was not fully fit, and a final decision on whether he will play the No. 2 singles will be made before Thursday's draw.

If Tipsarevic doesn't play, doubles specialist Nenad Zimonjic could step up, though the veteran hasn't played a live cup singles since 2008. The alternatives are 117th-ranked Dusan Lajovic, who has played one dead rubber, 227th-ranked Filip Krajinovic, yet to play in the cup, or doubles specialist Ilija Bozoljac, who has played four cup singles, all of them dead rubbers.

Even if Tipsarevic was fit, Djokovic will be under pressure to play all three days at Belgrade Arena, needing to win both of his singles and possibly be forced to team up in doubles with Zimonjic.

Djokovic, on a 22-match winning streak, said despite feeling exhausted from a grueling season, he was ready to deliver.

"I played and won a lot of matches lately which gives me a lot of confidence," Djokovic said.

He has won his last four tournaments, including the ATP Finals in London where he beat top-ranked Rafael Nadal 6-3, 6-4 in the final on Monday.

With Djokovic, Serbia is considered the favourite by the Czechs to win its second Davis Cup title.

"They are playing at home and Novak is on the team," the Czechs' Tomas Berdych said. "That is enough for their advantage."

Berdych, who has a 13-1 record in Davis Cup doubles with Radek Stepanek, believes the doubles will decide the winner.

"Doubles is definitely the most important point," Berdych said. "It happened for us many times in the past."

Djokovic said that although he has not played many doubles in recent years, he would be ready on Saturday if needed.

"It's a different tactical approach between doubles and singles," Djokovic said, adding that the decision whether he would play doubles depends on the result of the first-day singles on Friday.

Berdych and Stepanek played singles and doubles when the Czechs beat Spain 3-2 in last year's final in Prague. Berdych, who failed to qualify for the semifinals at the ATP Finals, said he would be ready to play all three matches against Serbia.

"It's the end of the season and I may not be as physically fit as when it started, but I'm ready to play all three matches," Berdych said. "Many players are already on holiday, but I bet many would change their position with us to play in the Davis Cup final."

Berdych, ranked 7th, has beaten Djokovic only twice in their 16 encounters, and never on a hard court.

"Tomas is one of the best players in the world and although he's never beaten me on a hard court, we have had a lot of long and tough matches," Djokovic said.

The Czechs are in the final for the third time in five years. Serbia won its only Davis Cup title in Belgrade in 2010, beating France. The Czechs defeated Serbia 4-1 in the quarterfinals in Prague last year, but Djokovic did not play.