The piano trio remains, for jazz, a format rich in possibilities, and with a player as gifted and as expressive as Michel Petrucciani on the bench, rewards abound. A skilled keyboardist, yet somewhat of a diamond in the rough in terms of concept, the diminutive French pianist had the full attention of his Blues Alley audience last night from the first notes of his opening piece, John Coltrane's "Impressions."

Rolling clusters of blues-tinted chords, chimelike single notes and a flowing movement were interspersed with a sort of strumming action and a two-fingered percussive attack so rapid that it lost all sense of staccato and became an unbroken line.

An expansive and inventive player, Petrucciani kindled fiery exchanges both with and between his companions, bassist Palle Danielsson and drummer Elliott Zigmund, in the kind of interplay that makes for very, very exciting listening. There is much individuality in Petrucciani's playing and his approach to the idiom is not only fresh and original but spontaneous from the word go. There were several delicately kneaded ballads in the set and it concluded with an improvisation that seemed to derive in part from Miles Davis' "All Blues," but gathered velocity and left that theme in the dust.

The trio performs again this evening.