UPDATE 4-Tennis-Lopez stuns ailing Del Potro to pull Spain level

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By Brian Homewood

MAR DEL PLATA, Argentina, Nov 21 (Reuters) - Spain pulled level with Argentina in the Davis Cup final on Friday when Feliciano Lopez stunned an ailing Juan Martin del Potro in four sets.

Lopez, 31st in the world rankings, won 4-6 7-6 7-6 6-3 in three hours 19 minutes to wipe out David Nalbandian's straight sets win over David Ferrer in the opening rubber.

Del Potro, already troubled by a toe injury, appeared to pull a muscle in his right leg in the sixth game of the fourth set and needed about 10 minutes of treatment.

"Tennis matches are like that," said Lopez, who was chosen by captain Emilio Sanchez Vicario ahead of the higher-ranked Fernando Verdasco.

"I was a bit nervous at the start, I got over it in the second set and began to believe in myself more. It was a victory over myself."

"To beat a top ten player this way, in a Davis Cup final away from home, is the happiest moment in my career."

"There were moments in the second and third sets where I felt I could not have played any better."