Behind a roaring serve, Roddick defeated Jonas Bjorkman 6-2, 7-6 (3), 6-4 Sunday in a clinching victory over Sweden that carried the United States into the finals.
The U.S. will play defending champion Russia for the title Nov. 30-Dec. 3, with the Americans hosting the finals for the first time since 1992. Russia defeated Germany 3-2 in the other semifinal in Moscow.
Roddick didn't drop serve in two singles matches, winning both in straight sets as the Americans ended a three-match losing streak against the Swedes dating to 1984.
After Roddick reeled off 16 aces to leave the U.S. ahead 3-1 in the best-of-five series, James Blake beat Simon Aspelin 6-1, 6-3 in a shortened finale to make the score 4-1.
Bjorkman replaced Thomas Johansson, the 2002 Australian Open who was scratched from reverse singles because of illness. Johansson won the second singles Friday against Blake.
"If you would have told me I could get through three sets with Jonas without getting broken I would have questioned your sanity a little bit," Roddick said.
The Americans have won the most Davis Cup titles (31), but the last came in 1995. The U.S. improved its record against Sweden to 8-3, ending the losing streak at the Scandinavium. Sweden, a seven-time champion, swept the U.S. and Pete Sampras 5-0 in the 1997 final, won the 1994 semifinal 3-2 and the 1984 finals 4-1.
"I have so much respect for the Swedish team," Roddick said. "For us to get by in an away tie at a place where we haven't had a lot of success in the past means a lot to our team."
Roddick, who held serve throughout the match on the fast indoor carpet, broke to lead 3-2 in the third set.
"If I would had just a little bit of a slip-up I would have been struggling," Roddick said. "Even when I didn't, I had to come up with a big serve on break points."
Bjorkman, at 35 the oldest player in the series, is still one of the world's top doubles players but has slipped to 55th in the singles rankings. Bjorkman played two matches when Sweden swept the U.S. 5-0 in the 1997 final.
"I think Jonas played a good match," Roddick said. "That's why he has been as successful as he has been."
Roddick, who is ranked fifth, improved his record to 5-2 against the Swede. Bjorkman lauded Roddick's serve, but said there is far more to his game.
"I think sometimes they don't give him enough credit on making a lot of returns himself," Bjorkman said. "He puts the ball in play a lot and sometimes it doesn't look that he moves well but he does."
Roddick has clinched nine Davis Cup series.
"I get very nervous," he said. "It's tough in the morning or the night before. But it's a really good feeling when you are able to clinch."
Bjorkman had his chances in the second set, but the Swede returned long at 15-40 and then Roddick aced to get to deuce. Roddick held to 3-2 with another ace and a forehand winner.
"It was frustrating," Bjorkman said. "I think the lady in the chair was way too nice to him because he took about 45 seconds going into that first serve. He should have had a time code violation there."
After missing a set point in game 11th, Roddick dominated the tiebreaker. He aced to go up 1-0 and had two mini-breaks en route to a 5-0 lead.
Next up is Russia, where the Americans lost 3-2 in the semifinals in Moscow last year. This time, there's the benefit of a home court.
"It's a lot better than playing away on clay against Russia," Roddick said.
On Sunday, Russia won both singles matches in Moscow, with Igor Andreev earning the decisive point by beating Philipp Kohlschreiber 6-3, 3-6, 6-0, 6-3. Earlier, Mikhail Youzhny defeated Philipp Petzschner 6-4, 6-4, 3-6, 6-3.
"I actually like that atmosphere, when you feel the adrenaline in every cell of your body and you step out knowing that the crowd will be behind you," Andreev said.
The Russians remained unbeaten at home since 1995. Last year, Russia downed Argentina to win its second Davis Cup title.
In the playoffs, Roger Federer won his second singles match of the weekend to put Switzerland even with the Czech Republic, but Radek Stepanek captured the finale to give the Czechs a 3-2 victory in Prague.
Federer, making his 2007 Davis Cup debut, beat Tomas Berdych 7-6 (5), 7-6 (10), 6-3. Stepankek then defeated Stanislas Wawrinka 7-6 (3), 6-3, 7-6 (4).
"This match reminded me a lot of the U.S. Open final against (Novak) Djokovic when I was down and came back, too," Federer said.
Djokovic helped Serbia reach the World Group for the first time by beating Chris Guccione of Australia 6-3, 7-6 (3), 7-6 (5) in Belgrade. Guccione replaced Lleyton Hewitt, who had a viral infection. Australia, a 28-time champion, lost 4-1 and was relegated to the Asia-Oceania zone for the first time since 1996.
"This is the best crowd I have ever played for," Djokovic said. "Finally, after so many years we have managed to get into the World Group."
In the other playoffs, it was: Austria 4, Brazil 1; Britain 4, Croatia 1; Israel 3, Chile 2; Romania 3, Japan 2; South Korea 3, Slovakia 2; and Peru 4, Belarus 1.