Troubled season over for Ivanovic

Ivanovic's first-round exit in Tokyo last week was her third straight defeat

Ana Ivanovic has withdrawn from the China Open and ended her 2009 season because of a respiratory infection.

The ex-world number one said she had been feeling unwell since arriving in Asia for the Pan Pacific Open in Tokyo.

The 21-year-old Serb blamed a series of minor ailments on being "over-trained" in the early part of the year.

She earned top ranking in June 2008 after her maiden Grand Slam triumph at the French Open, but has not won a single tournament this season.

"I guess having to withdraw from Beijing is an appropriate ending to a very disappointing season," Ivanovic said in a statement.

"I am sorry to my supporters who were hoping to see me play here in Beijing.

"It's very disappointing for me as well, to come here, see the amazing facility they have and not have the energy to be able to step onto court."

Despite my disappointments there is not a single doubt in my mind that I will reach the top again and win Grand Slams Ana Ivanovic

Ivanovic, who changed her service style after Wimbledon to protect her shoulder, said she has struggled to come to terms with her injury problems this year.

"Instead of being patient and accepting that my best form was almost impossible due to physical limitations, I was always over-thinking things, and I never dealt with it very well," she added.

"The season was a continuation of going from one disappointment to another. If I had dealt better with these setbacks, I would have had a lot more success.

"But despite my disappointments there is not a single doubt in my mind that I will reach the top again and win Grand Slams.

"I have a lot to look forward to. Now is the time to rest, recharge, and come back stronger."