Carrie Underwood is carrying quite the Friday schedule. The Country Music sweetheart was spotted yesterday in rehearsals for the Conde Nast Media Group's 4th Annual Fashion Rocks benefit, which will take place today. The concert is to honor fashion and music, combining music talents and supermodels wearing clothes by the world's leading designers. Underwood will be joined by fellow Country Music artist Keith Urban, as well as Christina Aguilera, Beyoncé, the Black Eyed Peas, Chris Brown, Mariah Carey, Rihanna and Justin Timberlake. The two-hour show will air Tuesday, Sept. 9, at 9 p.m. EST on CBS. Underwood also is expected to appear and perform at the multicast Stand Up to Cancer event tonight, along with fellow Country Music ladies LeAnn Rimes and Miley Cyrus. The event airs at 8 p.m. EST and CST across all major networks.