Sugarland has pulled out of Saturday night's Bryce Jordan Center performance as the opening act for Keith Urban.

"Due to an unfortunate illness to lead singer Jennifer Nettles, Sugarland will not be able to perform," a release from the Bryce Jordan Center states.

According to Sugarland's Web site, Nettle received "doctor's orders" to rest her voice for the next 10 days due to a viral tonsil condition.

Country superstar Keith Urban's concert will go on with "hopefully a replacement act," which has yet to be determined, according to the release.

Refunds will be available before show time if requested, according to the release.

BJC representatives could not be reached for comment.