POREC, Croatia — The Czech Republic reached its first Davis Cup final in 29 years today after securing an insurmountable 3-0 lead over Croatia by winning the doubles.

Radek Stepanek and Tomas Berdych defeated Marin Cilic and Lovro Zovko 6-1, 6-3, 6-4 to decide the best-of-five series.

"It's unbelievable," Stepanek said. "We didn't think we would cruise to a 3-0 lead against the powerful Croats."

On Friday, Stepanek withstood a record 78 aces and saved four match points against Ivo Karlovic in the longest Davis Cup singles in 20 years. Stepanek won 6-7 (5), 7-6 (5), 7-6 (6), 6-7 (2), 16-14 in 5 hours, 59 minutes.

The Czech Republic will take on either Spain or Israel in the final in December.

The Czechs opted to stay with the players who won the singles on Friday, and Croatia surprisingly picked its top player Cilic for the match in an attempt to stay in the series.

Stepanek converted the fourth match point with a smash, triggering wild celebrations by the thousands of Czech fans who outnumbered the Croat supporters at the Zatika hall.

It will be the Czechs' first final since their only Davis Cup triumph in 1980, led by Ivan Lendl. This is only the second loss for 2005 champion Croatia in 13 home matches in the Davis Cup.

Cilic, ranked 15th, reached the quarterfinals of the U.S. Open.

"I had problems recuperating after Friday's singles, but there is no excuse, the Czechs were better," said Cilic, who lost in five sets to Berdych on Friday.

Croatia's Karlovic was still recuperating from the marathon singles match and did not play doubles.