When pianist Mal Waldron and saxophonist Chico Freeman met in an unaccompanied jazz duo format at the One Step Down Sunday night, they turned their first set into one 40-minute improvisation. Chicago's 41-year-old Freeman is better known, for he has been the leader of countless recording sessions, but New York's 64-year-old Waldron, who has spent many years in Europe, set the tone for the evening: spare and devotional.

Waldron never hurried, never wasted notes; his two-handed chords were punctuated by pauses as he altered intervals in search of newer, richer harmonies. He quoted show tunes, jazz standards and gospel riffs -- much as his two mentors, Charles Mingus and Thelonious Monk might have -- but he incorporated them all into his patient, tender improvisations. Struck by Waldron's example, Freeman distilled his John Coltrane-influenced sound to succinct phrases.

The evening began with Freeman playing Islamic-sounding lines on his soprano sax over Waldron's slow gospel chords, creating a shared spiritualism. After several unaccompanied piano solos, Freeman switched to tenor sax and played a breathy ballad over Waldron's lightly swinging piano figure, creating a shared romanticism. When most jazzmen get in a duo setting, they rush to fill all the open spaces; Waldron and Freeman were wise enough to let the spaces remain.