…. so many aficionados considered him then and now Chicago’s leading post-war blues pianist. Spann played on most of [Muddy] Waters’ classic Chess waxings between 1953 and 1969, his rippling 88s providing the drive on Waters’ seminal 1960 live version of “Got My Mojo Working” (cut at the prestigious Newport Jazz Festival, where Spann dazzled the assembled throng with some sensational storming boogies).
~Bill Dahl (allmusic.com)