NEW YORK (AdAge.com) -- Fox's "American Idol" remains a giant -- though it's standing less tall than it has in the past.
The juggernaut search-for-a-singing-champ show saw total live-plus-same-day viewers fall 13% in its 10th-season debut last night, to about 26.1 million from approximately 29.9 million last year. On a live basis, however, viewership seemed flat, according to data from Nielsen.
Of greater concern for Fox, perhaps, is the drop-off last night's debut saw in terms of viewers between the ages of 18 and 49 -- the demographic advertisers covet most. Last night's telecast saw an approximately 18% decline in that category.
Keep in mind: Most networks would be happy to have 26 million people tune in to a single telecast, and there's no doubt that "American Idol" remains TV's most-watched show (and, as a result, the most expensive program on TV for advertisers).
Still, the show is aging and last night's debut marked one of its lowest-rated in some time. Viewing for "American Idol" peaked during season five in 2006, with 30.3 million viewers -- the last time any regularly scheduled show averaged over 30 million viewers per telecast, according to Brad Adgate, senior VP-research at independent Horizon Media. Audience levels have declined annually since season six.
Fox has some reason to cheer: Despite the absence of Simon Cowell, more than 25 million people tuned in, and TV reviews of new judges -- Steven Tyler and Jennifer Lopez -- have been favorable.
"Idol's" true levels this season won't be known for some time. For one thing, Fox has shifted its second episode to Thursdays, a much more competitive night than Wednesdays. For another, "Idol's" true buzz won't emerge until some of the contestants become better known and generate followings of their own.