Vocalist Willie Buck was a mainstay in Chicago clubs from the late 60s until the early 90s, when his friend and closest stage partner, the late keyboardist Johnny "Big Moose" Walker, suffered a stroke and stopped playing out. Buck all but quit performing too, but recently he's been gigging again with increasing frequency, appearing at the Checkerboard and a few other local venues; on Thursday, May 30, he has a set at the Chicago Blues Festival (see sidebar). Buck sings in a dark, intense baritone, his phrasing and timbre obviously patterned after Muddy Waters's rough-cut but emotionally rich style--a connection he underlines by filling his sets with covers of Waters's best-known songs, like "Forty Days and Forty Nights," "Trouble No More," and "Don't Go No Farther." Buck's erratic sense of time can make him a challenge for sidemen, however--which is where guitarist Johnny B. Moore comes in. Moore's comp work is crisp and rhythmically sure, and he has the extraordinary ability to keep his chording flawlessly in tempo even while he's playing one of his sharp-toned, restless lead lines. Born in Clarksdale, Mississippi, in 1950, Moore first heard the blues from elder statesmen like Jimmy Reed and Robert Nighthawk; he took up his instrument after moving to Chicago in 1964, and has said that the first song he ever learned was Muddy Waters's version of the Delta standard "Catfish Blues." He reached an international audience in the mid-70s as a member of Koko Taylor's band, and since 1987 he's made around half a dozen recordings as a leader--including 1997's Troubled World for Delmark and last year's Born in Clarksdale, Mississippi for the Wolf label. Consistently solid, these albums have earned him a reputation as one of the most versatile and knowledgeable Chicago bluesmen of the younger generation, equally comfortable with traditional acoustic fare and contemporary soul blues. He's most at home, though, when he's deep in the pocket of a driving postwar shuffle: with his stinging slide work in particular he evokes the fabled Delta-to-Chicago blues connection so powerfully it sometimes seems he's trying to summon the ghost of Robert Johnson or Elmore James. Friday, May 24, 9:30 PM, Rosa's Lounge, 3420 W. Armitage; 773-342-0452.