The superb Boston pianist Pandelis Karayorgis is spending the week in Chicago, renewing old musical acquaintances and making new ones. Tomorrow night he’ll take his Wurlitzer head-to-head with fellow pianist (and ARP synthesizer whiz) Jim Baker at Hotti Biscotti, along with drummer Steve Hunt, bassist and guitarist Brian Sandstrom, and electric bassist Nate McBride. But for me the most exciting gig happens on Thursday at Elastic, when the trio of Karayorgis, McBride, and clarinetist Guillermo Gregorio will reconvene to celebrate the recent release of Chicago Approach (Nuscope), a dazzling album recorded here in the fall of 2005. (Karayorgis also recently released a duo album with Ken Vandermark called Foreground Music on Okka Disk, but they won’t be playing together on this trip.)

Karayorgis collaborated regularly with McBride back when he still lived in Boston and appeared on Gregorio’s first album, Approximately (Hat Art, 1996), and Red Cube(d) (Hatology, 1999). He and Gregorio both share a strong affinity for the music of reedist Jimmy Giuffre and pianist Lennie Tristano, and in some ways the instrumental format of Chicago Approach suggests an homage to Giuffre’s great trio with pianist Paul Bley and bassist Steve Swallow. It includes a lovely reading of Giuffre’s “Variation” as well as a spin through “Spring Signs,” a piece by pianist Don Friedman, an associate of Tristano-disciple Lee Konitz. But close listening makes it clear that this trio has its own set of concerns. Nine of the 15 selections were freely improvised, but the spontaneous structures these musicians devise give the music an austere, composed feel. All three men are sharp listeners, reacting in a flash to one another’s gestures and darting melodic lines. On the surface the performances are subdued, but that belies the weight of the performances and the skilled on-the-fly harmonies.

Following the trio set at Elastic, Karayorgis and McBride will be joined by saxophonist Keefe Jackson and trombonist Jeb Bishop for a set that will include tunes by Karayorgis and Thelonious Monk.