MADRID -- Top-ranked Novak Djokovic joined Rafael Nadal in declaring he won't play again on the new blue-clay court at the Madrid Open after losing 7-6 (2), 6-3 to Janko Tipsarevic in an all-Serb quarterfinal on Friday.

Tipsarevic won for the second time in five matches against Djokovic, who last lost at this stage in November at the Paris Masters.

"I want to forget this week as soon as possible and move on to the real clay courts," Djokovic said. "Here you can't predict the ball bounce or movement. They can do whatever they want, but I won't be here next year if this clay stays."

Nadal lost to Fernando Verdasco on Thursday. After his loss, Nadal said he wouldn't return to the tournament unless it reverts to red clay. Djokovic described the new surface as slippery.

Tipsarevic had to save four break chances to force the first-set tiebreaker that he dominated. The seventh-seeded Tipsarevic broke Djokovic to go ahead in the second set and finished off the upset after Djokovic hit two late aces to save three match points.

Tipsarevic next plays Roger Federer, who defeated David Ferrer 6-4, 6-4. The blue clay didn't stop the 16-time Grand Slam champion from deploying his usual array of unreachable shots. He is unbeaten in 13 matches with the sixth-ranked Spaniard, who didn't help his cause by serving seven double-faults. Federer struck back-to-back aces to clinch the win, improving his record to 24-3 this year.

Argentina's Juan Martin del Potro used 10 aces to beat Alexandr Dolgopolov of Ukraine 6-3, 6-4 and reach the semifinal with Tomas Berdych.

The six-seeded Berdych defeated Verdasco 6-1, 6-2. The Spaniard made 24 unforced errors and showed little of the flare on display Thursday when he ousted Nadal.