The Americans trailed 2-1 entering the last day of the best-of-five competition and needed singles victories from Roddick and Blake to advance.

But Tursunov put Russia into the title match against Argentina by winning 6-3, 6-4, 5-7, 3-6, 17-15 for a 3-1 lead. His victory made the concluding match between Blake and Marat Safin inconsequential.

The Russians will host Argentina in December in their first Davis Cup final since they beat France in 2002 for their only title. Argentina beat Australia in the other semifinal.

In the 32-game final set on clay at Olympic Stadium, both players survived scares and held serve until Tursunov netted an easy forehand to go down 30-40 in the 11th game. He saved one break point, but hit two shots wide at deuce.

Tursunov then broke back to even it at 6-6 when Roddick sent a return wide after saving one break point.

The two then traded service wins until Roddick netted a forehand slice to give Tursunov his fourth match point. The Russian then sent a backhand down the line for the victory.

Roddick struggled from the start, losing his first service game. He lost it again in the second game in the second set, but broke back in the eighth game.

Roddick won only three points in his opponent's first five service games in the third set, but he held serve and broke at 6-5 to avoid a tiebreaker and stay in the match.

As Roddick gained confidence and Tursunov seemed to falter, they traded service wins until the Russian netted an easy forehand and Roddick converted his third break point with a backhand volley to take a 5-3 lead.

Tursunov, who was knocked out of the U.S. Open in the third round and struggled with his backhand in Saturday's doubles, was an unexpected choice by Russia coach Shamil Tarpishchev.

Nikolay Davydenko is Russia's best clay-court player, but he withdrew from the Chinese Open last weekend because of dizziness, and Tarpishchev instead picked Safin to play Roddick in the opening singles.

Safin defeated Roddick 6-4, 6-3, 7-6 (5) and Youzhny beat Blake 7-5, 1-6, 6-1, 7-5 on Friday, putting Russia ahead 2-0. The last time the U.S. rallied from a 2-0 Davis Cup deficit was in 1934 against Australia.