Feliciano Lopez and Tommy Robredo upset Jonathan Erlich and Andy Ram 7-6 (6), 6-7 (7), 6-4, 6-2 as Spain beat Israel at Torre Pacheco for the chance to win its fourth title this decade, and become the first team to win successive Davis Cups since Sweden in 1997-98.
"To be in the finals two years running is incredible," Robredo said.
The Czechs surprisingly paired Radek Stepanek and Tomas Berdych a day after they took nearly 10 hours to win the opening singles against host Croatia. Together, they defeated Marin Cilic, who lost to Berdych in singles, and Lovro Zovko 6-1, 6-3, 6-4 in a comparatively quick 2 hours, 16 minutes at Porec.
The victory advanced the Czechs to their first final since their only Davis Cup triumph in 1980, when Ivan Lendl led what was Czechoslovakia.
"We are very happy to be in the finals, but we won't be satisfied until we lift the cup," Stepanek said. "We will be outsiders in Spain, but we have been in that situation many times in the past and we hope to use it to our advantage."
Spain will be heavily favored for the final from December 4-6.
With the win over first-time semifinalist Israel, the Spanish have won 17 successive ties at home and 19 straight on clay since Gustavo Kuerten's Brazil beat them in 1999 at Lerida.
Spain lead the Czechs 3-2 in head-to-heads, including the last tie in 2004 which featured many of the present players; Lopez, Robredo, Rafael Nadal for Spain, and Stepanek and Berdych for the Czech Republic.
Nadal, injured during the U.S. Open, watched Lopez and Robredo struggle against the more experienced Ram and Erlich, who have won 13 doubles titles, including the 2008 Australian Open.
The Israelis rallied from 6-3 down in the second-set tiebreaker to win it 9-7 to level the set score. They came back again from 4-0 down in the third set but Lopez and Robredo hung on to win it 6-4.
In the fourth, Erlich had to be treated for a sore shoulder and lost service in the third game in what proved to be the decisive break of an intense match which lasted 3:46.
"It's tough to beat Spain on clay, even if we were healthy," Ram said.
Meanwhile, Stepanek and Berdych broke Cilic in the opening game of their doubles and rolled on at Zatika Arena, interrupted only by a 15-minute break at the start of the third set when some lights went out.
Stepanek converted their fourth match point with a smash, triggering wild celebrations by the thousands of Czech fans, who witnessed only Croatia's second defeat in a home tie.
"It's unbelievable," Stepanek said. "We didn't think we would cruise to a 3-0 lead against the powerful Croats."
In playoffs to make next year's World Group, only Serbia advanced on Saturday after beating Uzbekistan 3-0 in Belgrade.
Roger Federer didn't play doubles so Italy cut Switzerland's lead to 2-1 in Genoa; Jo-Wilfriend Tsonga won his second point for France to lead the Netherlands 2-1 in Maastricht; Mahesh Bhupathi suffered a groin injury and had to retire in the third set of the doubles as India led South Africa 2-1 in Johannesburg; Belgium led visiting Ukraine 2-1 in Charleroi; Sweden led Romania 2-1 in Helsingborg; Ecuador's Lapentti brothers won a five-setter to lead host Brazil 2-1; and Chile led Austria 2-0 in Rancagua.