Pop stars, models and Jeremy Piven. It’s a hot combination for “Fashion Rocks,” which airs Friday on CBS (9-11 p.m.) The annual concert at Radio City Music Hall, which has become an A-list event, has an impressive list of performers… many in interesting couplings. Mary J. Blige will duet with Usher; Fergie with Ludacris; Alicia Keys with Santana. Other performers include Maroon 5, Nickelback’s Chad Kroeger, Aerosmith, Avril Lavigne, Carrie Underwood, Jennifer Hudson, Jennifer Lopez, and Martina McBride. Presenters include Jessica Alba, Max Azria, Mischa Barton, Tyra Banks, Sean “Diddy” Combs, Francisco Costa, 50 Cent, Teri Hatcher, Tommy Hilfiger, Michael Kors, Irina Lazareanu, Denis Leary, Kimora Lee Simmons, Sean Lennon, Emily Procter and LeAnn Rimes. Piven, the star of “Entourage”, suits up as the host. “It’s totally uncharted territory,” Piven told the Associated Press. “Some people do extreme sports — you know, people like Laird Hamilton surf, like, 60-foot waves — I just, like, host things that I’m totally under-qualified to do.”