Just days before undergoing top-secret surgery for breast cancer, "Extra" spotted a smiling and carefree Sheryl Crow in Santa Monica. But in reality, her life has been anything but carefree; she's been battling a secret fight with breast cancer.

The announcement is the latest life blow to Sheryl, who announced just three weeks ago that her wedding to Tour De France champ Lance Armstrong was off. This news is a bizarre and shocking twist of fate, considering Lance is a cancer survivor himself.

Back in Sheryl and Lance's happier times, she said, "He reminds me everyday that the day I'm living now, I can't get back." And this chilling interview quote now resonates stronger than ever.

Today, the big question on everyone's mind is whether Lance knew Sheryl was sick when they split? The answer is no. Armstrong told reporters at a weekend cycling event in California, "I was shocked when I heard."

And People Magazine's Julie Dam told us Lance is devastated. "Lance says he's been in contact with Sheryl and her family and her doctors," Dam revealed. "And he's confident she's going to make a full recovery because she's such a strong person."

Only "Extra" has the new details about Sheryl's condition after undergoing minimally invasive surgery last Wednesday in Los Angeles. Insiders told us Sheryl's doctors are hoping for a 100 percent chance of full recovery. Nonetheless, she will undergo precautionary radiation treatment five days a week for 33 days.

On her Web site, Sheryl has a message for women everywhere: "See you doctor and be proactive about your health."

Sheryl now joins a list of superstar breast cancer survivors including Anastasia, Olivia Newton-John and most famously, Melissa Etheridge, who once said: "I've never encountered anything as powerful as cancer."

"Extra" has just learned that's Sheryl's good friend Melissa will stand in for her this Thursday at a rodeo in Texas. Sheryl's been forced to cancel her upcoming North American concert tour.