Carrie Underwood co-wrote "Cowboy Casanova," the lead single from her third studio album, Play On, and one of the biggest singles of her career, with Mike Elizondo and Brett James. Released in September of 2009, "Cowboy Casanova" became the fastest-climbing country single of the year and Underwood's eighth No. 1 hit. It's been certified double platinum and was nominated for an ACM Award. Inside, Underwood and James discuss writing the tune.