During two sold-out dates at the Hollywood Bowl this past weekend (June 9-10), mellow singer/songwriter John Mayer played the soul man, blues man, pop idol and guitar hero as well.

Sunday night's two-hour show was uneven, but its brightest moments were filled with impressive and even stirring axe work from both Mayer and his sideman, one-time Pretenders guitarist Robbie McIntosh. Still, Mayer's more lightweight, funk-dipped pop tunes just meandered about, lessening the impact of his strongest material.

Mayer was most effective when mining soulful grooves like those on the swaying, bluesy "Gravity" and the set-closing wish-for-a-better-tomorrow themed "Waiting on the World To Change." In songs like the anti-War "Belief" -- which recalls Sting a bit, but is certainly no "Fragile" -- Mayer's trying to be a deeper thinker and move beyond his guy-next-door demeanor. But will his large core audience of female fans originally smitten by his boyish charm let him grow?

The Hollywood Bowl dates, which are part of Mayer's "Continuum" summer tour, certainly showed him pushing to evolve without falling prey to too much jam band excess. He and his seven-man outfit, which included two horn players for texture beyond guitar and keyboards, were more about musical exploration than just serving up the hits.

Sunday night's encore led off with a round of acoustic songs that included a well-chosen cover of Bruce Springsteen's "I'm on Fire" and a sweetly gentle version of the sometimes wince-inducing hit "Your Body Is a Wonderland." Wrapping up with heartfelt "World," Mayer's gifts as a musician and growing range as a vocalist were evident, but the real passion came when he forgot the breathy-boy pop ditties and unleashed that guitar of his.

The bill also featured the quirky, clever pop and piano dazzle of Ben Folds, and the Zeppelin-influenced blues rock of Rocco DeLuca and the Burden.