Brad Paisley, Randy Travis and Carrie Underwood will all take part in American Idol's Grand Ole Opry week on Wednesday (March 18). Paisley will perform his new single, "Then," for the first time on national television. The single is from his forthcoming album, American Saturday Night. In addition, Travis and Underwood will perform a duet of "I Told You So," which Travis wrote. His version reached No. 1 on the country charts in 1988. Underwood's solo version is her current single. A new studio duet version of "I Told You So" will be available digitally the next day. American Idol contestants will select and perform songs popularized by Grand Ole Opry members on the episodes airing Tuesday and Wednesday (March 17-18). Paisley, Travis and Underwood are all members of the Opry.