One felt a little sorry for Al Jarreau at Wolf Trap Sunday after he confessed his fans insist he sing the same songs night after night. "Bear with me," he joked at one point. But as familiar as most of the tunes were, Jarreau didn't seem to be a prisoner of his own success. In fact, if anything, he resembled an escape artist, capable of wriggling out of every musical constraint he encountered.

His vocal elasticity and thematic ingenuity were particularly evident on "Take Five," the Dave Brubeck piece that's long been a staple of Jarreau's concerts. Improvising freely with his quintet, he rearranged the tune on the spot, whimsically playing with the meter, melody, harmony and rhythm until the tune took on a fresh vitality and momentum. Similarly, "We Got By," one of Jarreau's earliest hits, inspired a series of extemporaneous flights, colorfully executed and neatly resolved.

Jarreau got an assist from the flamboyant alto saxophonist Dave Koz when it came time to reprise "We're in This Love Together." To the crowd's delight, the two briefly engaged in Jarreau's old-fashioned "cutting contest," matching wits and intervallic leaps. Other songs, including the inevitable encore performance of "Spain (I Can Recall)," were also refreshed by Jarreau's desire to keep things interesting, not just for his audience but for himself.

The opening sets were devoted to smooth jazz performances by Koz and trumpeter Chris Botti. While Koz wowed the crowd with his keening alto and goofy choreography--he spent a lot of time on bended knee or hopping on one foot--Botti's atmospheric balladry and jazz-rock excursions were far more impressive, alluring and energizing by turns.