Andy Roddick put the holders USA into the semi-finals of this year's Davis Cup on Sunday with a straight-sets hammering of France's Paul-Henri Mathieu.

The 25-year-old triumphed 6-2 6-3 6-2 in the fourth rubber in Winston-Salem to give the US team an unassailable 3-1 advantage and secure a last-four tie away to Spain in September.

Roddick has now clinched Davis Cup ties for his country on 10 occasions.

The world number six was in sparkling form on his return to the scene of his Davis Cup debut seven years ago.

Mathieu simply could not handle the Roddick serve throughout the contest, which the 2003 US Open champion concluded in style with two aces.

In the dead fifth rubber, James Blake came from a set down to make the win even more emphatic with a 6-7 (4/7) 6-4 6-4 triumph over Richard Gasquet.

Spain beat Germany 4-1 in their last-eight clash - they had already sealed victory by going 3-0 up with a win in Saturday's doubles rubber.

On Sunday, Nicolas Kiefer defeated Feliciano Lopez in straight sets to ensure Germany avoided a whitewash. Earlier Fernando Verdasco had beaten Michael Berrer.

In the other semi-final, Argentina will play host to the 2006 champions Russia.

The home side started the final day 2-1 up against the Czech Republic and clinched the decisive fourth rubber when Tomas Berdych had to pull out of his match against Nikolay Davydenko after twisting his right ankle in the fifth set.

At the time of his retirement, Berdych was 3-6 6-2 7-6 (7/5) 3-6 2-1 up.

"I was feeling really great today," said Berdych. "But this is just sport. You can't do anything else."

Lukas Dlouhy beat home favourite Marat Safin 6-3 6-3 in the dead fifth rubber to make the final scoreline 3-2 to the Russians.

Russia, who have now won 16 consecutive ties at home, will next meet Argentina after they defeated Sweden 4-1 in Buenos Aires.

David Nalbandian secured Argentina's place in the last four with a thrilling 6-4 1-6 4-6 6-4 9-7 over Robin Soderling in the fourth rubber.

Juan Monaco beat Thomas Johansson in the meaningless final match.