Big-serving American Andy Roddick [Images] hammered an out-of-sorts Novak Djokovic [Images] 6-3, 6-2 on Friday to advance to the semi-finals of the ATP event at Indian Wells.

Roddick broke the third-seeded Serb twice in each set to book his place in the last four against world number one Rafael Nadal [Images], who crushed Argentinean Juan Martin Del Potro 6-2, 6-4 in a later match.

On a hot afternoon in the California desert, seventh seed Roddick swept through the opening set in just over half an hour on the stadium court at the Indian Wells Tennis Garden.

The second set went with serve until the error-prone Djokovic netted a backhand to be broken in the sixth game and trail 2-4.

World number seven Roddick then held serve before again breaking the Serb in the eighth to reach the semi-finals at Indian Wells for a third time.

Djokovic, who beat American Mardy Fish [Images] in last year's final, had not dropped a set during the tournament until being taken apart by Roddick in one hour, eight minutes.

"I don't think he had his best day by any means," Roddick told reporters after extending his win-loss record this season to 23-3.

"That obviously helps right away.

"I mixed up the pace pretty well and the chip was a pretty good neutralising shot for me. I was hitting it pretty firm and I didn't really miss any returns. I thought I played pretty well."

RUEFUL DJOKOVIC

Djokovic rued one of the worst performances of his career after slipping to his third defeat by Roddick in five meetings.

"There's not much to say," the Serb said after piling up 30 unforced errors and three double faults. "He played very solid. He didn't do anything special.

"It was all me making an incredible amount of unforced errors. This was one of the worst matches I have played."

"It's just one of those days when you really don't feel comfortable on the court," added Djokovic, who had been bidding to reach the last four for a third consecutive year at Indian Wells.

"I just didn't have any momentum. No feel for the ball, no movement, no solutions."

Nadal, champion here in 2007 and the top seed after winning three of the last four Grand Slam titles, broke sixth-seeded Del Potro four times to wrap up victory in one hour, 49 minutes.

The Spanish left-hander was delighted to triumph in straight sets after saving five match points before beating David Nalbandian [Images] 3-6, 7-6, 6-0 in the fourth round two days earlier.

"I'm happy," Nadal said after hitting 25 winners against Del Potro. "I won against the number six in the world. 6-2, 6-4 is a very good result.

"I happy about the beginning, the first set and then leading 2-0 but later I stop a little bit. I played bad against David but today I go on court with more clear ideas. I am playing well."

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