Johnny Copeland was one of the Houston-based guitarists of the 50s and early 60s who added rock-and-roll fire to the crisp, swinging Texas blues pioneered by T-Bone Walker in the 30s and 40s. The result was an urgent new music full of youthful exuberance and forward-looking rhythmic propulsiveness, a kind of Texas counterpart to what Ike Turner was doing in Memphis. Copeland's style these days combines the energy of his youth with a highly developed melodic and harmonic sense: his leads consist largely of sustained, shimmering phrases that weave their way through complex melodies; the melodies themselves often depart radically from traditional forms but nonetheless retain a powerful feel of soulful immediacy. Sometimes Copeland's perfectionism gets the best of himhis solos tend to sound the same from performance to performance, and he occasionally has to be reminded to depart from his set repertoire--but when he hits his stride his sound has a knife-edged clarity. He's also got a refreshingly uplifting approach-even his rowdiest barn burners are infused with celebratory affirmation instead of party-till-you-puke decadence. Saturday, Buddy Guys Legends, 754 S. Wabash; 427-0333.