Henin, Three Former No. 1s; Hingis Injured -- WTA Zurich Open Preview

Other seeded players include No. 2-seeded Russian and former US Open champ Svetlana Kuznetsova, Serb risers Jelena Jankovic and Ana Ivanovic, and willowy Slovak Daniela Hantuchova.

Missing the event will be homecountry hero and former No. 1 Martina Hingis, who is calling an early end to her season due to injury

"I'm very disappointed that I have to withdraw from the Zurich Open and that I can't play in front of my home crowd," said Hingis, who is hoping to come back strong in 2008. "I love the city and the tournament, both of which bring back so many good memories. I've done everything I can to be able to compete, but since Key Biscayne [in March at Miami] I've had problems with my hip, and they're still stopping me from playing any more tournaments, this year tournaments and even from practicing properly. I've therefore decided that I'm going to take as much time as it needs to get fully fit again."

The top four seeds in Zurich receive opening-round byes, but a few first-round encounters of note remain in (7) Hantuchova vs. Russian Dinara Safina, (8) Mauresmo vs. Wimbledon runner-up Marion Bartoli of France, India's Sania Mirza vs. (WC) Michaelaa Krajicek, Russian (WC) Maria Kirilenko vs. Tatiana Golovin (winner to face Sharapova), and (6) Williams vs. homecountry favorite Patty Schnyder.

Henin is likely headed for a semifinal showdown with either Mauresmo or Jankovic, while in the other semi Sharapova is the favorite to square off against either Williams or Kuznetsova.

In last year's final, the No. 2-seeded Sharapova outlasted Hantuchova 6-1, 4-6, 6-3.