BEIJING -- China Open organizers say Serena Williams has withdrawn from the tournament with an illness.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."
The tournament starts on Saturday in Beijing. Williams will be replaced by 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.