Hosts Czech Republic came within a point of winning the Davis Cup final after beating holders Spain in the doubles rubber here on Saturday to take a 2-1 overall lead.
Tomas Berdych and Radek Stepanek beat Marcel Granollers and Marc Lopez 3-6, 7-5, 7-5, 6-3 on the hardcourt of Prague's O2 Arena in three hours and 19 minutes.
"That's all we wanted," a triumphant Berdych, who is only 119th in the ATP doubles rankings, said after the game.
"We are still missing a lot, it's just one point, but we are looking ahead and we will do everything" on Sunday, he added.
On Sunday, Berdych, the world number six in singles, will take on fifth-ranked David Ferrer in a rubber pitting the teams' number one players against each other.
Stepanek, the world number 37 in singles, is due to face 11th-ranked Nicolas Almagro after that.
The Czechs are eyeing their first trophy since the country split with Slovakia in 1993, while former Czechoslovakia won the cup in 1980.
A win would hand them a rare team double after the women's team defended the Fed Cup here two weeks ago.
Spain, missing world number four Rafael Nadal, who is recovering from a knee injury, are looking to lift their fourth Davis Cup in five years, in addition to wins in 2000 and 2004.
But the holders' hopes suffered a blow on Saturday as Lopez and Granollers, ranked sixth and 10th in doubles, failed to overcome the Czech pair.
This all despite a boost that the Spaniards got from winning the ATP Tour Finals, where they lost only one game -- against Stepanek and India's Leander Paes.
Besides, both Berdych and Stepanek had played the singles rubbers on Friday.
Things looked bright for the Spanish pair as Stepanek, the world number four in doubles, lost his opening serve, which was enough for Granollers and Lopez to take the first set.
"I had a bad first serve and our opponents... played without any pressure, delivering incredible shots, serving amazingly," said Stepanek.
"But we told ourselves there is no way they can keep playing like that," he added.
In the second set, Lopez was the first to lose his serve but Berdych offered Spain a quick re-break.
But Lopez was in for more trouble as he struggled to come back from three set points down and finally conceded the fourth one to let the Czechs come level.
In the third set, games went with serve until Lopez offered two set points again and the Czechs converted the second one.
All but flawless throughout the rubber, Granollers lost his serve in the sixth game of the fourth set and that was all the Czechs needed to clinch their 12th Davis Cup doubles win together, against a single loss.
"I served very well today but in that game I couldn't make a single first serve and if you don't have one good serve against such players, it's pretty difficult," said Granollers.
"It was a close game. We were very good in the first set, and the second and third one were close," said Lopez.
"We tried our best and we are a little disappointed because we didn't win," he said.
In Friday's singles, Ferrer beat Stepanek 6-3, 6-4, 6-4 and Berdych then put the Czechs level after beating Almagro 6-3, 3-6, 6-3, 6-7 (5/7), 6-3.
Stepanek spent three hours on the court on Friday and Berdych an hour longer.
But they waved aside all concerns about weariness before Sunday's rubbers, insisting they would be ready for the climax of the 100th Davis Cup final.
"We have the best score we could hope for after day two," said Berdych.
"We're facing a terribly hard Sunday, but if you want to win the Davis Cup final, you can't expect to be done after Saturday."
"We have lots of will left, and I believe we'll manage to finish the job tomorrow," Berdych added.