Bluesman Willie has long been a cult figure around his home base in Willingboro, New Jersey--his first band, Captain Midnight and the Eldorados, was a tough-rocking R & B outfit that featured an aggressive young sax man named Clarence Clemmons. But Willie should be known as much more than the guy who gave Springsteen's sax blower his first big break: he's a superb sangwriter and musician in his own right. Although his guitar tone can be mellifluous and even tender, he bites off single-note phrases with the naked intensity of a Maxwell Street busker, and the Little Milton-like soulfulness of his voice is buttressed by a powerful timbre and a riveting emotional commitment. Willie tends to favor slick arrangements--his recordings on his own Energy label feature a Memphis-style horn section, a leather-chested vocalist named Yolanda Briggs, and a stripped-down show-lounge elegance--but make no mistake: he attacks his music with relentless ferocity. Burning beneath it is an emotional heat that can rile up even the most staid Jersey shore nightclub audience. Here in Chicago, home of the music he loves, he'll have something special to prove. Friday and Saturday, Rosa's, 3420 W. Armitage; 342-0452.