Roddick threw his hands up in triumph after Tursunov's final return landed long on the hard court in Portland's Memorial Coliseum. The mostly pro-American crowd went wild.
Roddick, ranked No. 6 in the world, improved to 6-0 in Davis Cup play this year.
"It's kind of like 'so close but so far away.' There's no celebration,'' Roddick said. "It's one match. The celebration will be saved for when we win, if we win.''
Roddick took the first set after he hit an 146-mph serve that No. 34 Tursunov returned long, ending a game that went to deuce four times. Roddick let out a growl after holding serve, and the U.S. fans went wild.
Roddick went up 2-1 in the second set when Tursunov hit a forehand into the net to finish off the break. He won the set with back-to-back aces.
Roddick broke Tursunov again to start the third set. While he high-fived U.S. captain Patrick McEnroe, Tursunov threw up his hands in disgust.
"If there are 12-and-a-half thousand people behind you and you can use them to help you win a tennis match, you would be stupid not to, right?'' Roddick said. "Other than cheating, I'll do anything I can to win.''
Mikhail Youzhny was scheduled to play 13th-ranked James Blake in the second match on Friday. Bob and Mike Bryan face Nikolay Davydenko and Igor Andreev in doubles on Saturday, before reverse singles on Sunday.
The best-of-five final is a culmination of a year's worth of international competition.
The once-dominant United States has 31 Davis Cup titles but none in 12 years, the longest span without an American victory. Pete Sampras last led the team to victory over Russia on clay in Moscow in 1995.
Roddick had 25 aces in the match, which lasted 1 hour, 53 minutes. Tursunov had eight aces.
Russia's captain Shamil Tarpischev pulled a surprise at the draw, leaving fourth-ranked Nikolay Davydenko out of the singles matches -- setting up the first match between Roddick and Tursunov.
"I wasn't playing my game,'' Tursunov said. "I was playing way too passive. I was playing not to miss.''
Davydenko comes into the Davis Cup final at the center of an investigation into unusual betting patterns during a loss to Martin Vassallo Arguello of Argentina at a match in Poland in August.
Betfair, an online gambling company, voided all bets on the match after unusually large amounts were wagered on the lowly ranked Argentine throughout the contest, even after he lost the first set 6-1. Davydenko retired with an injury in the third set.
Davydenko denies the allegations.
Tursunov is the lowest-ranked member of the Russian team, following Davydenko, No. 19 Youzhny and No. 33 Andreev.
Both Davis Cup teams include the same players from the semifinals, when the United States beat Sweden 4-1 and Russia defeated Germany 3-2.
The United States last hosted the Davis Cup final in 1992, in Fort Worth, Texas. Andre Agassi, Jim Courier, Sampras and John McEnroe defeated Switzerland.
Memorial Coliseum, which seats about 12,800, has hosted two previous Davis Cup events, in 1981 and 1984, both U.S. semifinal victories over Australia.
Friday's event was full of pageantry -- as well as enthusiastic fans. With an obviously pro-United States crowd, the Russians had their own smaller, but very boisterous, contingent.
Billie Jean King presided over the coin toss, and Nike co-founder Phil Knight was among the spectators.
Copyright 2007 by The Associated Press