There's something both eerie and fitting about hearing the American saxophonist Chris Potter in London in the week in which the jazz world prematurely lost the hugely influential Michael Brecker. The 36-year-old Chicago-born virtuoso is one of Brecker's natural heirs - capable of filling every hint of a space with a densely original chromaticism, yet regularly rising above the creative limitations of purely technical prowess.

Having paid plenty of dues to his sax heroes over the years, Potter sounds closer to an original music than he ever has with his current quartet, Underground. Part of the impetus has come from the arrival of the radical young keyboardist Craig Taborn, part from Potter's gradual embrace of vocabularies outside the African-American tradition.

The quartet played an unbroken two-hour set on Tuesday. The improvising and the ensemble-playing was almost always up to such an extended display, even if the edgy, hard-accented themes sometimes sounded more perfunctory. Guitarist Adam Rodgers played brittle, warped-bluesy runs between hustling chords and bottleneck atmospherics, Dave Holland's drummer Nate Smith was alert to every improvised diversion, and the remarkable Taborn repeatedly drew the music away from jazzy linearity toward an abstract soundworld of choppy accents, glowing tones and wide spaces on the Fender Rhodes.

Potter at times accompanied his sax lines with pad-clickings like a shadowy percussionist, which Smith delightedly commented on. R&B and soul grooves shifted to fragile reveries, Joni Mitchell's Ladies of the Canyon was a yearning bass clarinet feature, and the funky post- bopper Boots had the audience whooping with disbelief on Potter's ascending tenor solo. It's a band that sounds like a work in progress, but it's progressing fast.