Portishead unveiled a new set Thursday night at the Mayan Theatre in Los Angeles with a Coachella warm-up gig that left fans anxiously anticipating the real deal this Saturday night. What was supposed to be a VIP-only secret show (Quentin Tarantino, the Osbourne family and Mark Ronson were among the rumored expected attendees), quickly spread to the masses, with fans and radio contest winners let inside to get a taste of the band’s festival performance. Though attendees missed out on the lights and razzle-dazzle the group will be bringing to the desert, the show didn’t require any bells and whistles. Dressed nearly identically in dark T-shirts and jeans, the band (appearing as a seven-piece) tore through songs from their new record, Third, including “Silence,” “The Rip” and the staggering, aptly named, “Machine Gun.” Surprisingly, they offered up many songs off their debut, Dummy, including “Glory Box,” “Roads” and “Wandering Star,” the latter of which was given a softer, gentler, bass-and-vocals only remake, but only a scant few from their second effort, Portishead, including “Cowboys.” So how did they sound? Impressively pitch-perfect. Beth Gibbons’ voice soared operatically at points, revealing her true range reaches far beyond torch singer. Live, the band’s sonic wizardry is warmer and less alien, though no less fascinating and unique. When they finished their biggest hit, “Sour Times,” Gibbons waved her hand as if to say, “that was so-so” and shrugged, but the crowd’s roar served as a definitive rebuttal.