Both have played together in different contexts for decades, most famously with the Instant Composers Pool (ICP) Orchestra, a large ensemble of Dutch improvisers they co-founded with clarinetist Willem Breuker in 1967, which recently toured Europe and the United States this March and April.

Their duo set in Berlin was the opening act for The Ex, a group of Dutch avant-garde punk rockers. Thus, the audience was a mixture of free jazz aficionados and fans of The Ex (Bennink recorded a 2001 duo album on Atavistic Records with The Ex's guitarist, Luc Ex, entitled The Laughing Owl).Bennink's fierce and aggressive, yet highly virtuosic and humorous drumming made the set brilliant at times, seeming closer to punk rock than to jazz or more traditional projects like Jazz at Lincoln Center.

However, the duo never lost contact with the jazz tradition. Mengelberg's introspective, laid-back, but highly intense piano style is full of allusions to multiple jazz giants, from Monk, Powell, and Herbie Nichols to Lennie Tristano and Cecil Taylor.

The two famous Dutchmen added the usual theatricality to their performance. More than once, Bennink left his drum kit to play on the stage floor or hit his cymbals with his chair, while Mengelberg stoically improvised Powell-like single-note lines or hymn-like chords, in contrast to Bennink's thunder. What is most stunning about those two giants of European jazz is that, despite all the clowning and eccentricities, it all makes perfect musical sense and swings intensely without ever sounding old-fashioned.

Mengelberg and Bennink's duo revealed not only how vital and entertaining contemporary jazz improvisation can sound, but also that it appeals to an audience as diverse as the one at Berlin Kreuzberg, whose ovations were rewarded with two encores.