NOVAK Djokovic has kept Serbia's hopes of lifting the Davis Cup alive as he put his country level 2-2 with holders the Czech Republic by beating Tomas Berdych in straight sets.

Djokovic, the 26-year-old world number two, beat seventh-ranked, 28-year-old Berdych 6-4, 7-6 (7/5), 6-2 in two hours and 41 minutes for his 24th victory in a row.

Serbia's Dusan Lajovic will take on Radek Stepanek of the Czech Republic in the decisive fifth rubber on the hardcourts of a sold-out Belgrade Arena.

Propelled by a noisy home crowd, Djokovic relied on his serve in the first set, while Berdych tried to indulge him in long exchanges, combining a fast forehand with a wicked sliced backhand.

Both being fast servers, they had six aces each at the end of the first set, but Djokovic's play was slightly more precise, earning him ten break points against none for Berdych.

Djokovic capitalised on the tenth one he had in game ten, converting his fourth set point for a 6-4 lead after an hour.

In the second set, both held on to their serves safely until the ninth game nine in which Djokovic offered two break points, throwing his racquet in disappointment before hanging on.

The racquet did not survive the subsequent tie-break but Djokovic shook off his frustration in time to win 7-6 (7/5) in over an hour.

In the third set, Berdych started to accumulate the errors, offering two breaks to Djokovic who held on to his serve for a 6-2 win, putting the 2010 champions Serbia level with the visitors.

Serbia now depended on the 23-year-old Lajovic, the world number 117, who replaced 36th-ranked Janko Tipsarevic, out with a heel injury.

The hosts are also missing 76th-ranked Viktor Troicki over a doping ban.

Playing their third final in five years, the Czechs in turn have an interim captain for this tie as Vladimir Safarik replaced Jaroslav Navratil who was hospitalised with a pulmonary embolism.

In Friday's singles, Djokovic, the recently-crowned ATP World Tour Finals champion, beat Stepanek 7-5, 6-1, 6-4, and Berdych then saw off Lajovic 6-3, 6-4, 6-3.

On Saturday, Berdych and Stepanek won the 14th of their 15 Davis Cup doubles rubbers together as they swept Ilija Bozoljac and Nenad Zimonjic 6-2, 6-4, 7-6 (7/4).