Hunkered down, sometimes to the point that his tenor saxophone appears to be parallel with the floor, the burly Fred Anderson suggests a cosmic sumo wrestler–a noble fighter grappling with destiny. His music does little to alter that impression. The tone is dark and expressive; the improvisations are freewheeling and pantonal, yet they retain a songlike accessibility that has escaped many better-known players of “the avant-garde.” Anderson holds three important niches in Chicago jazz history: he helped found the Association for the Advancement of Creative Musicians (AACM); his bands have served as early proving grounds for such musicians as trombonist-composer George Lewis and reedmen Chico Freeman and Douglas Ewart; and his own uncompromised musical vision had a direct influence on the generation of musicians represented by the Art Ensemble of Chicago. As has been the case so often over the last 20 years, Anderson will share the front line with trumpeter Billy Brimfield, an unheralded marvel of crisp lines and fiery invention; behind them, drummer Ajaramu and the much-recorded Malachi Favors–best known as bassist for the Art Ensemble–will dance their own separate-but-compatible rhythmic ballet. Thursday, 8 PM, Club Lower Links, 954 W. Newport; 248-5238.