Serena Williams has withdrawn from next week's China Open due to illness and Venus Williams has withdrawn due to a back injury, a source at the WTA has confirmed.
Early Thursday morning, the China Open's official account tweeted via the Chinese Twitter service Weibo that Serena had withdrawn from the tournament due to the flu and would be replaced by Romina Oprandi. Later in the afternoon, Serena tweeted her flu-like symptoms.
Serena has a history of keeping her post-U.S. Open schedule notoriously light. Since 2005 she has played Beijing only once, in 2009, which also happens to be the first year it was made mandatory and the last year she qualified for the WTA's season-ending Championships.
One school of thought was that Serena would make a push to end the season at No. 1, a feat she could have accomplished if she played well in the fall. She was the only top 10 player to skip Tokyo and now with her withdrawal from the WTA's mandatory tournament in Beijing the path to No. 1 gets tougher. Victoria Azarenka and Maria Sharapova continue to widen the point gap (both made the quarterfinals in Tokyo this week and are scheduled for Beijing next week) and if Azarenka makes the final in Beijing, then Serena has no chance to finish No. 1 regardless of how well she plays -- if she plays -- in the Championships in Istanbul.