Martina Navratilova Martina Navratilova

Martina Navratilova has breast cancer, but she expects to make a full recovery.

"It was my personal 9/11," the tennis legend told Good Morning America's Robin Roberts (herself a breast cancer survivor) of the February day she received the diagnosis. "I was shocked because I was so sure [the calcification] was benign, and I found out and I was devastated. Physically, I couldn't think, I couldn't move. I was useless."

Navratilova, 53, was diagnosed with ductal carcinoma in situ (DCIS), a non-invasive form of breast cancer. Because the cancer is in one breast and has not yet spread, there is a "very small chance" of a relapse.

Although she was surprised by the news — because "I've been healthy all my life" — the 18-time Grand Slam champion said she only has herself to blame for taking four years between mammogram appointments. She said she was feeling "100 percent fine" at the time of the diagnosis.

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