Since his classic recordings with pianist Memphis Slim in the 1950s, Matt Murphy's work has been a standard against which blues guitarists are judged. He developed his style in the burgeoning postwar Memphis blues scene, where jazz and R&B overtones were added to the sounds of traditional bluesmen like Howlin' Wolf and Rice Miller. Murphy learned his lessons well; his technical dexterity is unsurpassed, and he's capable of augmenting his slickness with the raucous, heavily amplified roadhouse aggression that distinguished postwar Memphis blues from the mellow, nightclubby styles being honed in California during the same period by such Texas emigres as T-Bone Walker and Lloyd Glenn. These days Murphy's shows are schizophrenic experiences; after a few awesome opening numbers ranging from smooth Memphis blues to swinging bebop and driving funk-jazz fusion, he sits back and plays sideman to a vocalist who purveys amiable renditions of blues standards. Certainly an enjoyable evening, but be sure to arrive early for Murphy's part of the show; he'll have you doubting your eyes and ears. Tonight, B.L.U.E.S. Etcetera, 1124 W. Belmont; 525-8989. Saturday, Shades, 21860 N. Milwaukee, Prairie View; 708-634-2583.