Britney Spears, Mariah Carey join Christina Aguilera on talent shows

MALIBU, Calif. -- NBC's "The Voice" and Fox's "The X Factor" may both be battling for viewers this fall, but don't expect the conflict to extend to their marquee names.

At a press event Sunday to promote the third season of "The Voice" (8 p.m. Sept. 10), coach Christina Aguilera wished fellow Mickey Mouse Club alum Britney Spears well on her entry into the singing-contest genre as a judge on "X Factor" (8 p.m. Sept. 12).

"I came up with Britney. Mickey Mouse Club, we were very close. Our paths have always crossed and they continue to cross. I welcome her to this family of fun and entertainment and finding new talent," Aguilera said. "I don't know what she's going to offer specifically, but I know she's a pro and she's going to give, I think, great advice."

The field of singing-competition pop stars will become even more crowded in January, when Mariah Carey joins Fox's "American Idol," with another judge yet to be named.

"I welcome these very talented women," Aguilera said. "You know this business, especially in my genre of pop, (people) pit us against one another and women against women and this and that. I'm not down for that."

As new performers arrive on the other shows, it's possible that Aguilera and her coaching colleagues -- Cee Lo Green, Adam Levine and Blake Shelton -- could take temporary leaves during future seasons of "The Voice."

With the singing competition now scheduled for two cycles a year, it becomes likelier the current coaches may not all be available every season because of other professional obligations, such as touring and recording.

In a musical chairs of sorts, other performers who have time could come in and fill those seats while any of the originals are busy, with them returning when they are available, executive producer Mark Burnett said.

"We decided when you've been on the show, that's your chair for life," he said, "never to be replaced."