"The X Factor" was thumped on its U.S. TV debut, with American audiences preferring comedy "Modern Family" in their millions, ratings figures showed on Thursday.

After months of hype and bold predictions by its creator Simon Cowell, just 12.1 million Americans tuned in for the debut of "The X Factor" on Fox -- about half the audience for the most recent season of "American Idol".

Instead, "Modern Family" -- the affectionate ABC mockumentary that won big at the Emmy Awards last weekend -- drew 14.3 million viewers to make it the most-watched TV show of Wednesday night, early numbers for Nielsen media research showed.