STUTTGART, Germany -- Li Na of China beat Nicole Vaidisova of the Czech Republic 6-1, 6-2 on Monday in the first match of the Porsche Grand Prix.
Li next faces nine-time Grand Slam champion Serena Williams, who had a first-round bye. Williams is playing for the first time since defeating Jelena Jankovic in the U.S. Open final three weeks ago and regaining the No. 1 ranking.
"The U.S. Open is not the end of the year," Williams said. "I hope to do well in the last tournaments of the year."
She lost in the Stuttgart quarterfinals last year to Svetlana Kuznetsova, and she could run into the Russian again at the same stage this week.
Venus Williams is seeded sixth and is in the opposite half of the draw, meaning the sisters cannot meet until the final. The two are also playing doubles. They won the Olympic gold medal in Beijing.
Jankovic also had a first-round bye, as did Dinara Safina and Elena Dementieva. Dementieva will play Sybille Bammer of Austria in the second round. Jankovic meets Alona Bondarenko of Ukraine, who stopped Eleni Daniilidou of Greece 7-6 (5), 6-1.
Bammer downed German wild card Tatjana Malek 4-6, 6-2, 7-5 from a break down in the final set and saved two match points.
Ana Ivanovic and Maria Sharapova are the only top-10 players missing from the indoor tournament. Last year's winner, Justine Henin, has retired.
