Novak Djokovic joined Rafael Nadal in declaring he won't play again on the new blue clay court at the Madrid Open after losing to Janko Tipsarevic 7-6 (2), 6-3 Friday in an all-Serb quarterfinal.
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," the top-ranked 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."
On the women's side, Serena Williams eased past Maria Sharapova 6-1, 6-3 to advance to the semifinals. Also making the semis was top-ranked Victoria Azarenka, who rallied past French Open winner Li Na 3-6, 6-3, 6-3.
Azarenka agreed with Nadal and Djokovic in their criticism of the court.
"You feel unstable sometimes, actually, a lot of times," she said. "But right now there is no point on talking about it. After the tournament, all the players can get together and discuss it."
Nadal lost to Fernando Verdasco on Thursday. Afterward, the Spaniard 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 completed 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 sixth-seeded Berdych defeated Fernando Verdasco 6-1, 6-2. The Spaniard made 24 unforced errors and showed little of Thursday's flare in his victory over Nadal.
Williams opened strong, hitting six aces and making two early breaks to take the first set. Sharapova broke at love to even the score at 2-2 in the second set, but she quickly squandered her break with a costly sixth double-fault to fall behind for good. Williams sealed her seventh straight win over Sharapova with a slam.
"Playing Maria you have to be really ready because she does everything really well," Williams said. "I felt relaxed out there, and when I play relaxed, I play better."
Williams improved to 11-0 on clay this year. She will face Czech Lucie Hradecka after she upset U.S. Open champion and fifth-seeded Sam Stosur 7-6 (8), 7-6 (6).
Azarenka, who has won four titles this season, used her powerful groundstrokes to take a 4-0 lead in the second set before holding off Li's late charge. The Belarusian will face Agnieszka Radwanska, who beat American Varvara Lepchenko 6-4, 6-4.