After watching John Mellencamp Saturday night at Summerfest, it is difficult to believe that back in the mid-'70s -- as Johnny Cougar -- he was groomed as the next David Bowie.

Not since the heyday of Bob Seger has anyone come to identify heartland rock and roll like Mellencamp. Fittingly for a blue-collar rocker, Mellencamp wore a blue shirt.

Playing to the healthy (if not sold out) Marcus Amphitheater crowd, Mellencamp opened his summer tour with a mix of new tunes from his upcoming CD "Life, Death, Love and Freedom," deep album cuts and a steady stream of the meat and potatoes hits on which he has built his career.

Playing guitar or energetically dancing the length of the stage Mellencamp certainly did not resemble the guy who suffered a heart attack shortly after a Summerfest gig in 1994.

Over the years Mellencamp's left leaning politics, his affiliation with Farm Aid and his fearlessness to voice his opinion have made him a target for criticism, but he has no problem backing it up.

In a call for unity, he recounted the racism witnessed toward the African-American singer in his teenage band. "Our Country," one of the evening's biggest sing-alongs, got its widest airing in a Chevy commercial. (Mellencamp summed it up simply by equating the audience who heard the song in the ad with the audience who would have once upon a time heard the tune on AM radio.)

During "Jack and Diane," Mellencamp asked everyone to call someone on their cell phone for a sing-along, and even grabbed a fan's phone for a quick chat.

Make no mistake; these were Mellencamp's people and they were on their feet for the first dozen songs, as Mellencamp and his six-piece band cranked up fan favorites "Small Town," "Pink Houses," "Lonely Ol' Night" and "Rain on the Scarecrow."

"Check It Out" and "Paper and Fire," a pair of songs that employed violin and accordion arrangements, got lost in the shed's mix. Aside from the solo acoustic ballads and blues tunes, this was a garage band cranked up to 11.

Opener Lucinda Williams (who headlines July 3 at the Harley-Davidson Roadhouse) played a short set that began with a rough patch. Bailing on a few tunes, she finished strong with the band kicking into a string of rockers in including "Honeybee," a funky "Joy" and leftfield cover of the Doors' "Riders on the Storm."

(Note of appreciation to whoever selected the music played between sets. The mix of tunes by the likes of Howlin' Wolf, Lightnin' Hopkins and others going back to pre-war artists was a small touch that set a definite vibe for the evening.)