China Open organizers say Serena Williams has withdrawn from the tournament with illness.
The tournament's official Chinese-language microblog posted a message late Thursday saying: ''This is regrettable news and we hope Serena Williams will get well soon.''
Her place in the tournament, which starts its qualifying rounds on Saturday in Beijing, will be Switzerland's Romina Oprandi.
Williams' own Twitter account carried a short message saying ''Flu no fun,'' but made no mention of the China Open. Williams also missed last year's tournament with an injury.