WASHINGTON - American Serena Williams withdrew on the eve of her opening match at the WTA Cincinnati Masters due to back injury, which forced her to have no chance to give better scope to her strength in her scheduled first-round battle against qualifier Zarina Diyas.

The 23-time Grand Slam champion, who experienced the same back spasms in the Rogers Cup final which gave the title to Canadian Bianca Andreescu, suffered the second blow just hours before her scheduled match began.

Serena, almost 39 years old, mentioned in a statement that she stood poised to play and hope was still looming on Tuesday morning, but she finally disillusioned as her back remained not right.

The injury, however, has aroused the concern over the 39-year-old player prior to the US Open.