Spain will play Argentina in the final of the 2008 Davis Cup after knocking out holders USA.

Another Rafael Nadal claycourt masterclass saw Spain clinch victory over the US in the fourth rubber of their semi-final, a result which set up November's trip to South America.

The world number one was in merciless form against Andy Roddick and his 6-4 6-0 6-4 victory in Madrid's Las Ventas bullring gave the Spanish an unassailable lead.

"Today I play an almost perfect match and it is very, very exciting," said Nadal. "I shocked myself with some of the winners I played, it was near perfect tennis."

Feliciano Lopez later beat Sam Querrey 7-6 7-6 to make the final score in the tie 4-1 to the hosts.

Meanwhile, Argentina secured their place in the final for the second time in three years after Juan Martin del Potro powered to victory in the decisive fifth rubber against Russia's Igor Andreev.

Del Potro, who recently won four ATP titles in a row to rocket up the world rankings, demolished Andreev 6-4 6-2 6-1 to secure an overall 3-2 victory for the home side in Buenos Aires.

With the tie delicately poised after Nikolay Davydenko defeated David Nalbandian, Del Potro knew a solid performance would be required to quell the growing confidence in the Russian ranks.

And the 19-year-old made the perfect start as he broke the Andreev serve in the opening game before holding the rest of the way to take the opener at a canter.

The Argentinian claimed the second set in even more comfort, breaks in the fifth and seventh games securing a 6-2 win as world number 19 Andreev struggled to get to grips with the power of his opponent.

The writing was on the wall by the time the third set got under way, and world number 13 Del Potro wasted no time putting the match to bed, breaking the Russian's serve in the first, third and seventh games to ease the South Americans into the final.

"It's a dream for sure," said Del Potro. "Last night I couldn't sleep and now I'm living the dream."

Earlier, world number seven Nalbandian looked as though the pressure might be off Del Potro in the final rubber when he won the first set against Davydenko only for the Russian to hit back to secure an impressive 3-6 6-3 7-6 (7/2) 6-0 triumph.

It was Nalbandian's first-ever Davis Cup singles defeat on home soil.

The final will take place in Argentina from November 21-23.