Serena Williams has pulled out of next week's tournament in Tokyo citing fatigue, the Kyodo news agency reports.
"I'm disappointed to have to withdraw from the Pan Pacific Open, which I was very much looking forward to playing this year,” Williams said in a statement. “Unfortunately with the number of matches I have played throughout the summer I need more time to properly recover."
After winning her fifth U.S. Open title, Williams said she was looking forward to playing doubles with her sister Venus in Asian events. The world No. 1 is still entered in the Premier event in Beijing, which begins on Sept. 30. Serena has only played the Asian swing five times in her career, twice in Tokyo (in 2000 and 2002) and three times in Beijing (2004, 2005 and 2009).
World No. 3 Maria Sharapova is also out of Tokyo and the rest of the Asian swing due to bursitis in her right shoulder. Sharapova said she hopes to return for the year-end WTA Championships.