CHICAGO — As the headliners of Saturday's fourth annual Hard Rock Cafe Rockfest, Metallica had a battle on their hands — and this time, the fight wasn't with Napster.

Topping a bill that included Kid Rock, Stone Temple Pilots, Barenaked Ladies and others, the hard-rock group — and all 12 bands that performed — had to fight for the attention of the nearly 100,000 people in attendance, who were bombarded with constant advertisements by the show's many sponsors.

"How's everyone doing at the world's biggest corporate rock concert?" Guster's Ryan Miller asked early in the day, reminding concertgoers of the festival's vast sponsorship, which led to its getting dubbed "the Hard Rock Cafe Rockfest presented by Oldsmobile Alero."

"Has anyone purchased an Oldsmobile Alero yet? You know, it's not your father's Oldsmobile," Miller joked.

Rockfest began with a bang in 1997 with what stands as the largest one-day ticketed music event in history. Roughly 380,000 people attended the inaugural festival in Dallas featuring the Wallflowers, Bush and Jewel. The festival has a reputation for hosting top talent. Last year's Atlanta show, which attracted 127,000 people, included the Offspring, Live and Sugar Ray.

This year, for $65 (plus $20 for parking), music fans were treated to a diverse lineup that also included Vertical Horizon, Veruca Salt and the Tragically Hip.

Puttin' On The Hits

But Kid Rock and Metallica were the obvious show-stealers among the dozen bands on the day's bill, which featured mostly short, hit-laden sets. Both bands' hour-long performances included pyrotechnics, special appearances (Kid Rock during Metallica's set; caged strippers during Kid Rock's) and loads of hits.

Metallica, all four members dressed entirely in black, opened with "For Whom the Bell Tolls" (RealAudio excerpt) and played favorites from throughout their 19-year career. During the band's performance of its current single, "I Disappear," the crowd eagerly provided vocals to the opening, "Hey hey hey" line.

"I think most people came here to see Metallica," said Jason Cornwell, former MTV "Real World" cast member and star of the upcoming film "The Private Public." "I know I did." Cornwell was on hand to emcee various portions of the festival and introduce some of the bands. (Sonicnet.com's parent company, Viacom, also owns MTV.)

Kid Rock opened with "Devil Without a Cause" (RealAudio excerpt), from his hit album by the same name, rapping with partner Joe C in front of an enormous inflatable middle finger. Following a hip-hop cover of Grand Funk Railroad's "We're an American Band," Kid Rock and crew closed with his current single, "American Bad Ass" (RealAudio excerpt).

Earlier, Stone Temple Pilots entertained the audience with a set that included only a few songs from their latest album, No. 4. "Wicked Garden" and "Sex Type Thing" (RealAudio excerpt), from their debut, Core, showcased singer Scott Weiland's powerful voice and enigmatic lyrics.

Weiland, sporting a raspberry Mohawk, told the crowd, "It's been a long time since we played Chicago. It's good to be back." He later added, "You kids better stick around because later Kid Rock and I are gonna f--- each other onstage." The crowd roared. The act never occurred.

Band Dresses Up Set

Barenaked Ladies' quirky blend of roots-rock and rap made them an awkward co-headliner, but they managed to entertain rock fans with their between-song banter and ear-friendly hits. Dressed in matching baby blue pants and yellow dress shirts (buttoned to the top), the group performed favorites "Brian Wilson" (RealAudio excerpt) "If I Had $1,000,000" and "One Week" (RealAudio excerpt).

Singers Steven Page and Ed Robertson showed off their assorted voices with a closing pop and rap medley that included Eminem's "The Real Slim Shady," Britney Spears' "... Baby One More Time" and the Bloodhound Gang's "The Bad Touch."

"The highlight for me, aside from Kid Rock's entire set, was the Barenaked Ladies' medley," said concertgoer Eric Heiker, 25. "It was a fun way to mock pop music."

Rockfest's afternoon performers, led by pop-rock groups Third Eye Blind, Tonic, LuvjOi and Guster, played flawless, energetic sets marred only by fans clad in black Metallica shirts who yelled obscenities at them and threw various objects toward the stage.

Keyboardist Jeremy Dean of Nine Days — who played an 11 a.m. set that included their hit "Absolutely (Story of a Girl)" and the upcoming single "If I Am" — said, "We didn't get hit with too many things, though someone threw a water bottle full of rocks at our bass player. All in all, I think there were a lot more people enjoying what we were doing by the end of the set than by the beginning."

Ads Abound

Above the giant stage hung a Hard Rock Cafe sign equipped with a full-scale model Alero, but this year's festival also was supported by Discover Card, Motorola, Pepsi (Wild Cherry and Mountain Dew, specifically) Sam Goody, Sony Playstation and Entertainment Weekly, all of whom attacked the young adult demographic largely represented at the concert with billboards, constant commercials (on video screens on and around the stage) and loads of "free sh--," as the announcers giving away T-shirts, cell phone cases and other stuff said.

"I didn't think about [the many sponsors] until we pulled up and saw Oldsmobile and Mountain Dew and ... whatever and said, 'Wow, there's a lot of people sponsoring this,' " Nine Days drummer Vince Tattanelli said.

"But, I went to the Hard Rock Cafe last night, and I ate free food and watched myself on TV, so corporate sponsorship can't be that bad," Dean added.

In general, the massive crowd seemed to agree with Dean's sentiments. People watched each of the acts attentively and then used the 15- to 30-minute set breaks to get in a game of Playstation or fill-up their official Hard Rock Cafe logo cup with Dew or Budweiser.

"I don't care about corporate sponsorship as long everyone is happy," Heiker said. "The companies are happy because they get to sit in the VIP [section]. The bands are happy, because they get paid a ton of money. And the fans are happy, because they get to see so much music for a decently priced ticket."

Thomas Jackson Weaver III, head of TBA Entertainment Corporation, the producers of the festival, added this in a statement: "Our goal is for Hard Rock Cafe Rockfest to be a vertically integrated, comprehensive initiative. The promotions of our corporate sponsors are a big part of the overall Rockfest experience."