World No. 1 women's tennis player Amelie Mauresmo of France has pulled out of this week's Porsche Grand Prix tennis tournament in Germany because of an injury to her right shoulder.

Mauresmo was set to play Michaella Krajicek of the Netherlands. The French player said she does not know if she will play in the Kremlin Cup next week in Moscow.

Lisa Raymond replaced Mauresmo in the draw as the highest-ranking loser in qualifying but lost to Krajicek in the second round (6-4, 6-2). Krajicek next takes on French player Tatiana Golovin, a 6-4, 6-3 winner over Iveta Benesova of the Czech Republic.

Fourth seeded Russian Nadia Petrova ousted Anna-Lena Groenefeld of Germany, 6-3, 6-4. Jelena Jankovic of Serbia, the tournament's eighth seed, needed three sets to get past Tsvetana Pironkova of Bulgaria, 4-6, 6-2, 7-5.

Fifth seed Patty Schnyder of Switzerland made the quarterfinals with a three-set win over Shahar Peer of Israel (7-6, 2-6, 6-4). Schynder plays third seed Elena Dementieva of Russia in the final eight.

Meanwhile, Daniela Hantuchova of Slovakia scored a straight-set win over Dinara Safina of Russia to reach the quarterfinals, (6-2, 6-2).

Mauresmo is the latest top player to pull out of the Stuttgart tournament because of injury. U.S. Open champion Maria Sharapova of Russia, Serbia's Jelena Jankovic, defending champion Lindsay Davenport and sisters Venus and Serena Williams of the United States, and Belgian stars Kim Clijsters and Justine Henin-Hardenne also decided to skip the event.

Some information for this report provided by AP and AFP.