World number one Lindsay Davenport and Russian Maria Sharapova withdrew from the Advanta Championships in Philadelphia on Tuesday due to injuries and illness.

The loss of the top two seeds was another huge blow to the tournament which has already seen the withdrawal of Venus and Serena Williams.

American Davenport was forced out of the $585,000 indoor event with flu while world number three Sharapova suffered a thumb injury in training, leaving defending champion Amelie Mauresmo as the highest seed left in the event.

Davenport and Sharapova indicated they expect to be fit for the season-ending WTA Tour Championships which begin next week in Los Angeles.

"I am looking forward to getting healthy and defending my year-end number one ranking at the WTA Tour Championships," said Davenport in a statement.

The absence of Davenport and Sharapova cleared two major hurdles from Mauresmo's path as she chases a third straight Advanta title.

After a first-round bye the Frenchwoman opens her account against Japan's Ai Sugiyama, who advanced on Tuesday with a 7-5 6-4 win over Czech Iveta Benesova.

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