Fox’s “American Idol” remains the undisputed king of primetime, but it may be showing its age.

For the first time, the 7-year-old show has failed to build upon the previous season’s premiere night rating. When 33.4 million tuned in on Jan. 15, it repped an 11% falloff from the record 37.4 million who tuned in on the opening Tuesday a year ago.

One night later, about 30.5 million viewers tuned in, with Fox again crushing the competition despite seeing declines of about 15% vs. the same night last season.

It’s too early to draw any real conclusions from “Idol’s” premiere, but its performance figures to be under even more of a microscope this year. Show, which was TV’s most-watched series with more than 30 million viewers a night last season, lost a bit of luster down the stretch last spring amid a less-than-stellar season for music talent.

“My only expectation this year was that it would be huge again and be the biggest thing in TV,” said Fox alternative topper Mike Darnell. “I look at those numbers still can’t believe I can wake up in the seventh season of a TV show and see it do 12 million more viewers than the show next to it.

“There’s ‘Idol,’ and then there’s the rest of TV. I can’t look at it any other way.”

As for the drop, Darnell said he didn’t think it mattered.

“This show has defied gravity for so long,” he said. “After six years of being up every year, it’s almost like it’s a meaningless drop. … It’s such a juggernaut at this level that no one will ever want to compete with it.”

NBC looks to be the net with the best solution, as its unscripted counterprogram-ming (weight loss series “Biggest Loser” and gameshow “Deal or No Deal”) have held up reasonably well.

“Deal,” which has shown surprising resiliency this season for the Peacock, actually improved upon its perf opposite “Idol” on the same night a year ago. “Idol” did dent “Deal” on a week-to-week basis (down 14%), but that was nothing compared with the declines of 30% or more for ABC’s “Supernanny” and “Wife Swap” and CBS’ struggling gamer “Power of 10” once “Idol” entered the fray.