Sheryl Crow (search) will not perform at Saturday's Live 8 (search) concert in Paris, part of the worldwide Bob Geldof-organized event to raise awareness of poverty in Africa.

"Due to substantial logistical and personal challenges Sheryl will be unable to appear at the Paris Live 8 event July 2," according to a posting on her Web site.

Although the 43-year-old singer won't be able to attend the show, she is asking fans to support the cause.

"Please don't let Sheryl's absence in Paris dampen your enthusiasm," the posting said.

Concerts also are scheduled Saturday in London, Moscow, Berlin, Rome, Tokyo, Philadelphia, Barrie, Canada, and Johannesburg, South Africa.