Jennifer Lopez and Stephen Tyler: Will they be as good as Simon and Paula?

Jennifer Lopez and Steven Tyler will join Randy Jackson on the long-running Fox show 'American Idol.'

Jennifer Lopez and Steven Tyler will join Randy Jackson as "American Idol" judges next season, after months of turnover and speculation about the future of TV's top-rated show.

With pomp rivaling that of a U.S. Supreme Court appointment, Fox finally assembled the new pieces of the "Idol" panel that will be returned to its original three-member format for season 10.

Actress-singer-dancer Lopez and Aerosmith frontman Tyler will have the job of trying to match the offbeat chemistry of former judges Simon Cowell and Paula Abdul.

"This is 'American Idol'!" host Ryan Seacrest said after the new judges joined him on stage at the Forum arena, where the final national audition for next season's singing contest was held Wednesday.

The announcement was made before a crowd of several thousand who had gathered to try out, some cheering loudly for the cameras and all hoping to make it to the next round, when they'll be judged by the revamped panel. The mini-show was streamed live online by Fox.

Tyler said he wanted to join the show because "it's being a part of something much bigger than yourself. ... I want to bring some rock to this rollercoaster and show if you've got the heart, the talent, the feeling to do this you could be the next American Idol."

"I'm so excited," said Lopez, who scored a reported $12 million to join the show. "I'm looking for the next Michael Jackson."

The likely Lopez-Tyler pairing had been reported so frequently that Fox would have had to produce Betty White and 50 Cent instead to generate any surprise.

Cowell announced last January that he planned to leave to launch a new talent show for Fox in 2011, with newcomers Ellen DeGeneres and Kara DioGuardi exiting this summer. Abdul left in 2009 over a contract dispute.

Jackson will be the only original judge when "American Idol" returns in January.

Though gone, Cowell wasn't forgotten at the news conference that followed the judges' unveiling.

The new judges as well as series producers were asked about the loss of Cowell and how much the acid-tongued Brit meant to the ratings.

"Simon is irreplaceable, no question about that," said executive producer Nigel Lythgoe. But he and fellow producer Ken Warwick said that the new judges will bring their own personalities to the mix.

The show has a valuable newcomer in Jimmy Iovine, chairman of Interscope Geffen A&M Records, a division of Universal Music Group, which this season is replacing Sony Music Entertainment as the label that develops, distributes and markets "Idol" finalists. Lythgoe said Iovine would bring his own expertise and style to the show.

Lopez made it clear she has no plans to become the new Simon.

"I believe in tough love, but I'm an artist myself," she said. "I could never be cruel to another artist."

Lythgoe, an original "Idol" producer now back on the show, took a swipe at some of the winners who emerged during his two-year absence. After early idols Kelly Clarkson and Carrie Underwood, he said, "Then we start running out of idols."

"We've got to go back to creating an American idol," he said.

Among other changes the new season will bring, the producers said that contestants won't be forced to stray from their favored genre: country singers can sing country songs; rock singers won't have to sing folk songs. Also, there are no plans to have celebrity mentors come on the show, as was common in seasons past.

Of course, Lopez and Tyler loom as the biggest changes, and the pressure is on them to help "American Idol" reinvent itself for the new season, when it will try to stem a ratings slide and bring in younger viewers. The show's audience has been gradually aging, and advertisers prefer to pitch to young adults.

But Fox and the show's producers didn't match the new judges to the target audience when it comes to age: Lopez is 41 and Tyler is 62. Jackson is in the middle at age 54.

Lopez, who wore a sparkling silver cat suit, got the full diva treatment as she took the stage clouded in special-effects smoke.

She also arrived with dubious star wattage, given that her last few films have tanked at the box office and she hasn't triggered any real excitement in the record world in years.

Lopez's films include "Selena," ''The Wedding Planner" and most recently "The Back-Up Plan." She has appeared as a mentor on "American Idol."

She was part of the "Fly Girl" house dancers on the comedy show "In Living Color," in 1990, before becoming a backup dancer for Janet Jackson.

"On the 6," Lopez's first album, came out in 1999 and launched a career in pop, Latin, hip-hop and R&B. "Love?" is the latest CD from the Grammy winner, who has twins with husband Marc Anthony.

Meanwhile, Tyler, whose band is four decades old, could hardly be called a fresh face.

Tyler brings a colorful and tempestuous history with him to the show. He's fought with his band mates, been in rehab for prescription drug abuse and took a fall off a stage in 2009 that forced cancellation of Aerosmith's summer tour. He also, like many rockers, seemed to show the effects of many years of pounding rock 'n' roll, as several news conference questions had to be repeated because he didn't hear them clearly.

"American Idol" was the nation's favorite program last season, the seventh time it's held that position. But it showed rare vulnerability, beaten in the weekly ratings several times by ABC's "Dancing With the Stars."

A total of 24.2 million viewers watched the ninth season's final duel between Lee DeWyze and Crystal Bowersox, compared to the nearly 29 million viewers who saw Kris Allen claim victory over Adam Lambert last year.