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Phil Mickelson, shown at the U.S. Open on June 22, has found out his mother has breast cancer.

updated 11:51 p.m. ET July 6, 2009

SAN DIEGO - Six weeks after Phil Mickelson announced his wife had breast cancer, his mother was diagnosed with the disease and is to have surgery later this week.

The San Diego Union-Tribune reported on its Web site that Mary Mickelson discovered she had breast cancer last week. She is to have surgery Friday at the MD Anderson Cancer Center, the same hospital where Mickelson’s wife, Amy, had surgery last Wednesday.

Mickelson’s sister, Tina, told the newspaper she wanted to make her mother’s condition known so she could receive the same outpouring of support and prayers that meant so much to Amy Mickelson.

Mickelson has not spoken publicly since the U.S. Open where he was a runner-up for a record fifth time.

His parents live in the same San Diego house where they raised their three children. Mary Mickelson was honored in 1998 as “Mother of the Year” by the San Diego chapter of the March of Dimes. She said at the time, “I don’t know if I’ve done anything extra than other mothers. We’ve always been involved and have just been there.”

Mickelson said at Bethpage Black that it was “highly unlikely” he would play the British Open, and said his schedule the rest of the year depended on his wife’s battle with cancer.