Jennifer Lopez, Steven Tyler expected to join show

Pieces of Fox’s “American Idol” puzzle continue to fall into place.

With Kara DioGuardi out of the way, the stage is now set for Fox and the “Idol” producers to finally, at long last, unveil the show’s new judging panel.

Unless there’s an 11th hour change of heart by one of the parties — or Elton John suddenly decides he needs a bit more pocket change — Jennifer Lopez and Aerosmith frontman Steven Tyler are expected to be officially added to the show in the next few days.

Such an imminent announcement comes out of necessity: The judges need to be in place by mid-September as the next round of auditions begin. And Randy Jackson alone can’t send contestants to Hollywood, dawg.

Jackson’s continued involvement with “Idol” has never really been in doubt; returning exec producer Nigel Lythgoe referred to him as the show’s “barnacle” in an interview with Daily Variety last month — and he meant it in a positive way.DioGuardi, on the other hand, had appeared to be on the outs for some time.

DioGuardi’s father, who’s running for the U.S. Senate in New York, even recently told a TV show there that his daughter hadn’t been informed of her fate on the show. (Insiders disputed that fact, however.)

She knows now. Fox kicked off the Labor Day weekend late Friday by announcing DioGuardi’s exit.

News, of course, wasn’t a surprise, as most observers had expected DioGuardi’s exit as part of ongoing changes on “Idol.”

“I felt like I won the lottery when I joined ‘American Idol’ two years ago, but I feel like now is the best time to leave ‘Idol,’ ” DioGuardi said in a statement. “I am very proud to have been associated with ‘Idol’ — it has truly been an amazing experience.”

DioGuardi’s two-season “Idol” stint received mixed reviews.

In her first year, DioGuardi was the fourth wheel, added to a panel that had been operating well as a threesome for years.

In her second season, DioGuardi’s presence was overshadowed by the arrival of Ellen DeGeneres.

But DioGuardi brought bona fide music industry credentials to the table. She worked in A&R at Warner Bros. Records, and as a successful songwriter who wrote music for Pink, Kelly Clarkson and Carrie Underwood.

“Kara was a great addition to our ‘Idol’ family,” said Mike Darnell, prexy of alternative entertainment, Fox Broadcasting Co. “I’ve been fortunate to get to know her well, and have always been amazed by her eye for talent and her commitment to developing and mentoring artists. She will be missed, and we wish her continued success.”

Move makes Jackson the only remaining judge on the show from last season. Original judge Simon Cowell departed at the end of this past season, while DeGeneres announced last month that she wouldn’t be back for a second year as judge.

DioGuardi’s exit bolsters expectation that “Idol” may return to a three-judge format this January. The show’s decision to expand to four judges has garnered criticism, as its running time has frequently spilled out of its timeslot to accommodate everyone’s opinions.

Besides Lopez and Tyler, industry vet Jimmy Iovine has been reportedly in talks to provide a role on the show, but nothing further has been announced.

In discussing Lopez’s addition to the show, Lythgoe told Daily Variety that audiences “know she’s a good actress. And as J-Lo she had some great pop records. If she joins, I’m happy.”

And in the case of Tyler, Lythgoe said he liked the rock star’s unpredictable persona.

“He has come through that whole rock ‘n’ roll circus,” Lythgoe said. “Why wouldn’t you want a legend there? You never know what he’s going to say. That, as a TV producer, you’re interested in.”

But once the judges are in place, the real work begins — breathing new life into a TV franchise that, while still hot, has taken plenty of critical knocks over the past year.

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