Spain will meet Argentina in the Davis Cup tennis final after the Spaniards beat defending champions the United Staes and Argentina beat Russia.
In Madrid world number one Rafael Nadal clinched their semi-final with a comprehensive victory over Andy Roddick in the first of the reverse singles, however the tie in Buenos Aires went to the 5th and deciding match with teenager Juan Martin del Potro beating Igor Andreev in straight sets.
Del Potro, two days short of his 20th birthday and playing his first home Davis Cup tie, won 6-4 6-2 6-1 as Argentina avenged their 2006 final defeat by the same opponents.
Earlier, Nikolay Davydenko hauled the Russians back into the tie by beating a tired David Nalbandian in 4.
Argentina will host Spain in November's final after chalking up their 13th successive home win, a run stretching back to 1998.
