Carrie Underwood commands the attention of thousands of screaming fans while performing onstage night after night. But, surprisingly, the singer has a very real fear of being surrounded -- a situation which even led to panic attacks.

"I'm horrible in crowds; I just get so nervous," Carrie tells Allure magazine. "This happened to me when I was in high school, before all of this. I would start having panic attacks in Wal-mart. I do not like shopping in close quarters; I just can't do that."

Drawing an imaginary square around herself to illustrate her point, she emphasizes, "This is my space. And I'm really weird about it."

So how does the 27-year-old beauty handle the situation when she has to shop? Carrie reveals she actually goes to great lengths to make sure she looks as 'unglamorous' as she possibly can, in dramatic contrast to her stunning public image. And, of course, she often saves her shopping until midnight!

"I wash the make-up off ... and I'm in a ponytail, glasses, my sweatpants," she says.

And if someone still recognizes her? "People won't tell me, 'Are you Carrie Underwood?' They'll say, 'Wow, you look like Carrie Underwood!"

Carrie is in the midst of her Play On tour with special guests, Craig Morgan and Sons of Sylvia.

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