LOS ANGELES -- The debut of Simon Cowell's "The X Factor" played second fiddle to "Modern Family."

On a competitive night of fall debuts, Fox's singing contest kicked off Wednesday with an audience of 12.1 million viewers, according to preliminary Nielsen Co. ratings.

The real glory went to ABC's Emmy-winning "Modern Family," which earned a leading 14.3 million viewers.

Among advertiser-coveted young adult viewers, the ABC 8-10 p.m. sitcom duo of "The Middle" and "Modern Family" topped "X Factor" by 7 percent.

Still, Fox pronounced itself more than satisfied.

"The X Factor" performed "within our expectations" and was a success for Fox, said Mike Darnell, the network's president of alternative entertainment.

"The X Factor" will return Thursday night with another two-hour episode.