BELGRADE, Serbia (AP) -- The pressure will be on Novak Djokovic to lead Serbia to a Davis Cup title in front of the home fans.
Janko Tipsarevic, the country's No. 2 player, is doubtful against defending champion Czech Republic because of a chronic heel injury.
Tipsarevic said Wednesday that he was not fully recovered. A final decision on whether he will play singles will be made before Thursday's draw.
If Tipsarevic sits out, doubles specialist Nenad Zimonjic could step in, though he hasn't played a meaningful Davis Cup singles match since 2008. The alternatives - 117th-ranked Dusan Lajovic, 227th-ranked Filip Krajinovic or doubles specialist Ilija Bozoljac - have never played in one.
Even with a healthy Tipsarevic, Djokovic would be under pressure to play all three days at Belgrade Arena. He may need to win both his singles matches and team up in doubles with Zimonjic.
Djokovic is exhausted after a grueling season. But he's also on a roll, riding a 22-match winning streak.
''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 Monday.
The Czechs insist Serbia is the favorite to win its second Davis Cup title.
''They are playing at home, and Novak is on the team,'' top singles player Tomas Berdych said. ''That is enough for their advantage.''
Berdych, who has a 13-1 record in Davis Cup doubles with Radek Stepanek, predicts the doubles will decide the champion.
''It happened for us many times in the past,'' Berdych said.
Djokovic hasn't played much doubles in recent years, but he said he would be ready Saturday if needed.
''It's a different tactical approach between doubles and singles,'' Djokovic said, adding that the decision will depend on the result of the two singles matches Friday.
Berdych and Stepanek played singles and doubles when the Czechs beat Spain 3-2 in last year's final in Prague.
''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,'' said Berdych, who failed to qualify for the semifinals at the ATP Finals. ''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 seventh, has beaten Djokovic only twice in their 16 meetings, 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.