Svetlana Kuznetsova is pulling out of next week's event in Moscow.
Writing on her Twitter account, Kuznetsova said "my health issues won't al[low] me to play in my home country tournament in Moscow! I have to end this difficult season now and recover."
Kuznetsova, who won the title in Beijing last year, fell in the first round earlier this week and said she had not been able to prepare because of illness.
"After U.S. Open, I practiced hard for a week in Moscow. I was supposed to leave on Tuesday for Tokyo so I'd have five days to practice and everything," she was quoted saying on the WTA website.
"I got sick. From Sunday to Saturday, one week, I wasn't home, I didn't go out, I didn't do any fitness, I was in bed. I didn't have time, but that's how it is."