Matt Freed, Post-Gazette Ken Susi of Unearth gets ready to jump into the crowd during the band's performance at Ozzfest.

It's written somewhere in the heavy metal bylaws that when Ozzfest comes to town, the temperature must exceed 90 and the sun must beat down with great force on the darkness below.

		Online only: The OzzBlog Read Tim McNulty's coverage of OzzFest from earlier in the day ... includes audio and photos

Maybe that's why the usual sea of black wasn't a sea of black at all Tuesday at the Post-Gazette Pavilion but a rainbow, with a shocking number of people in white and a lot of bare flesh. Much of it was covered in body art, mostly ink on the back but also fresh paint on the front of topless young females.

As for Ozzy, he chose to stick with jeans and black shirt (long sleeves) when he made his historic headlining appearance on the second stage in the asphalt parking lot.

It climaxed a 9-to-5 shift of metal with the likes of Atreyu, Strapping Young Lad and Black Label Society. The solo set, a break from Black Sabbath, gave Ozzy the chance to play some songs that hadn't been heard at Ozzfest in years.

The first thing we heard from Ozzy was "I love you all!," a rare moment of affection in a day designed for aggression. The Wizard of Ozzfest proceeded with solo faves like "I Don't Know" and "Mr. Crowley" (an odd one in the daylight) shuffling around the stage and firing the water canons with boyish enthusiasm. Black Label's Zakk Wylde had a big hand in Ozzy's set, driving the songs with old-school squealing guitar leads.

Vocally, Ozzy sounded good, though maybe a tad wobbly for the stuff of a live album. The set picked up serious momentum at the end with a "Crazy Train" that didn't require him to sing the chorus even once, "Mama, I'm Coming Home," the prettiest song of the day, and a no-holds-barred version of Sabbath's "Paranoid."

"Thank you and good night!" Ozzy yelled, adding, "I don't even know what ... time it is."

It was right around 5 o'clock, time for the main stage. It began with a gaggle of long-haired pretty boys called Dragonforce, an '80s throwback band from England that is way into "Lord of the Rings" and other fantasy worlds. They rocked this one with the operatic vocals of ZP Theart and the kind of fast and fancy guitar work you find in the record store.

If Jefferson Airplane had become Jefferson Zeppelin instead of Jefferson Starship, they might have sounded like Lacuna Coil. The Italian band jumped to the big stage with yin-yang vocals delivered by singers Cristina Scabbia and Andrea Ferro, wearing matching white shirts and ties. Perhaps the most impressive thing about Lacuna was how they met at center stage and all head-banged through the instrumental breaks while overcoming the vertigo.

Despite being from Italy, they sang in English, not that it mattered much considering you couldn't make out a word of the beautiful noise. A surprise highlight was a cover of Depeche Mode's "Enjoy the Silence," a risky but amenable choice for the Ozzfest crowd.

Jamey Jasta, the singer from Hatebreed, yelled, "Are you ready to turn the entire lawn into a pit?!" The answer was "well, no." But the band was still a big hit with the more angry and muscular people in attendance. Hatebreed is a textbook hardcore metal band with machine-gun rhythms and a singer in camo shorts and a baseball cap barking like a drill sergeant. He sent "Proven" out to people who support "aggressive music ? metal, hardcore and punk rock" (an inclusive gesture) and sent another out to the survivors of child abuse. "I know you're out there," he said. He was right. No laughing matter.

So, what do they hate? Hard to say. The new record is called "Supremacy," but it's not a race thing. As Jasta explained, "It's about supremacy over whatever holds you back." You get the feeling that what Hatebreed hates above all else is wimps.

Avenged Sevenfold gets the prize for best set design, with a commando skeleton backdrop, a skull with wings, arena ramps and very hi-tech lighting. The band, which cross-pollinates with the Warped Tour, is a metal hybrid that's sludgy, with frequent dips into melody. Guitarist Synyster Gates executed the best guitar solo of the day, combining technique, flash and melody. Avenged got the crowd up and shouting with a pounding cover of Pantera's "Walk," sent out to the late Dimebag Darrell, and really ignited with "Bat Country," one of the better songs of the day.

By the time Disturbed hit the stage, the natives were getting restless and the circle pit Hatebreed wanted finally appeared on the lawn. When singer David Draiman asked for a show of lighters, he got instead a spirited display of waste management. The metalheads were burning their trash, giving security a chance to use their highly efficient fire extinguishers.

On stage, Disturbed got "Down with the Sickness" as Drainam, bald and menacing, delivered some of the best and most unexpected "waaahs!" over a clean, powerful thrust of nu metal. In tune with its poppy side, Disturbed mixed in its cover of Genesis' "Land of Confusion." In tune with its political side, Draiman struck a rare chord of dissent, saying, "Maybe it's a difference of opinion, but I give much more value to the life of every U.S. soldier ? much more than our president does."

System of a Down, quite simply, blew everyone away, hitting the stage like Queen on speed. The band, which rose from the baby stage all the way to Ozzfest headliner, has an avant-garde streak with a jolt of Zappa weirdness and Korn explosiveness. The metallic songs take all sorts of unexpected twists, from reggae to prog to exotic Arab melodies.

Singer Serj Tankian, born in Beirut, owned the best pipes of the day, soaring and spazzing through a set of songs, heavy on last year's excellent "Mezmerize." Guitarist Daron Malakian got the full lawn lighter effect that Disturbed wanted with his beautiful vocal on "Lonely Day."

Malakian stopped to tell the crowd that a shortage of oil isn't the problem. What the networks don't tell you, he said, is that, "What you don't have, America, is your mind."

Not only did System go the high art route, with abstract paintings on the screens, the band had the broadest range of emotion and subject matter of the day.

The fact that a heavy metal crowd can embrace a quirky avant-garde band from Lebanon shows that minds can indeed be open at Ozzfest.