No horn man gets deeper into a solo than Chris Potter. But his relentless improvisations go beyond the melodic and harmonic explorations we’ve come to expect from saxophonists: he also dissects, recombines, and resurrects rhythmic ideas with an authority that recalls Sonny Rollins and Wayne Shorter, two of the very best at rhythmic inventiveness. For my money, the 35-year-old Potter is one of the three or four best soloists of his generation; a key member of vibrant working ensembles led by Dave Douglas and Dave Holland, he regularly earns ovations that out-thunder those for his onstage colleagues. He experimented with electronics on his 2002 album, Traveling Mercies, and for Underground (Sunnyside), a quartet date out this week, he’s made a radical shift in instrumentation. There’s no bass; the low notes emanate occasionally from Wayne Krantz’s electric guitar but more often from Craig Taborn’s retro-chunky Fender Rhodes, and the presence of two chord instruments allows for some dense layering of harmonies and colors. The songs also incorporate more rock-oriented elements: the opener, “Next Best Western,” washes in on a funky backbeat; “Nudnik” updates 70s fusion via Fender Rhodes and Potter’s smart, busy tenor solo; and “Celestial Nomad” channels the introspective side of John McLaughlin during his Mahavishnu days. Throughout, Potter proves himself a reedman for all seasons: without changing his rigorous approach to improvisation, he makes his solos fit perfectly within the tough grooves that drummer Nate Smith uses to spark the quartet. His gigs at Jazz Showcase kick off a national tour supporting Underground. See also Saturday and Sunday. Fri 2/3, 9 and 11 PM, Jazz Showcase, 59 W. Grand, 312-670-2473, $25.

Art accompanying story in printed newspaper (not available in this archive): photo/Michael Jackson.