TORONTO?- Venus Williams has withdrawn from the Rogers Cup due to an illness.

Williams says she wasn't feeling well so she went to see the doctor Sunday. She was diagnosed with a viral illness and says she is "extremely disappointed" she won't be able to play in Toronto.

Qualifier Zhang Shuai steps into Williams' first-round match Tuesday against Ana Ivanovic. Lourdes Dominguez Lino got the extra spot in the draw.

The strong Rogers Cup field still includes Williams' sister, Serena, and Caroline Wozniacki, Maria Sharapova and Kim Clijsters.