(Getty Images)

(Getty Images)

NEW YORK -- Tennis great Martina Navratilova has been diagnosed with breast cancer but she says her prognosis is excellent.

Navratilova, 53, told Good Morning America that she has a non-invasive form of the disease called ductal carcinoma in situ, or DCIS.

The athlete said she cried after being informed of the diagnosis following a routine mammogram.

"That was my personal nine-eleven," she said, referring to the day she found out -- Feb. 24.

"I was devastated. Physically I couldn't think, I couldn't move."

Navratilova said she had a lumpectomy and will begin six weeks of radiation therapy next month.

The nine-time Wimbledon women's singles champion said she put off having an annual mammogram for four years.

A surgeon at UC San Francisco says DCIS strikes almost 70,000 American women a year and that "there's only a one-percent chance of anyone with this diagnosis would die of breast cancer."