”American Idol” slipped a bit on Wednesday but still towered over everything else in primetime, lifting Fox to victory on a night when ABC’s ”Modern Family” was the top scripted show in demos.

According to preliminary nationals from Nielsen, ”American Idol” averaged a 6.4 rating/18 share in adults 18-49 and 20.6 million viewers overall from 8 to 9:30 p.m. , down vs. last week but up vs. the comparable night of a year ago. In most current averages for the season, the music competition series is off about 6% in 18-49 and up 2% in total viewers vs. last year. After peaking with a 7.1/19 in the demo at 9:30, ”Idol” gave way to rookie comedy ”Breaking In” (2.5/6 in 18-49, 7.3 million viewers overall), which was on par with last week and ranked second among the broadcasters in 18-49.

CBS earned a solid second-place finish even though ”Survivor” (3.0/9 in 18-49, 10.7 million viewers overall), ”Criminal Minds” (3.2/8 in 18-49, 12.8 million viewers overall) and ”Criminal Minds: Suspect Behavior” (2.2/6 in 18-49, 8.7 million viewers overall) all dipped. ”Suspect Behavior” retained a nothing-special 69% of its ”Criminal Minds” lead-in among adults 18-49, and fell behind NBC’s ”Law and Order: SVU” in all key categories at 10:30.

At ABC, ”Modern Family” continues to perform well opposite ”American Idol” (3.8/10 in 18-49, 9.6 million viewers overall), remaining the night’s No. 1 scripted show in 18-49; it also figures to grow by about 2 full ratings points in same-week DVR playback, based on recent trends. The net opened the night with ”The Middle” (2.0/6 in 18-49, 7.1 million viewers overall) and ”Better With You” (1.6/5 in 18-49, 5.5 million viewers overall), both up a tick vs. their most recent originals, while 9:30 entry ”Cougar Town” (2.2/6 in 18-49, 5.6 million viewers overall) again saw a big dropoff from its ”Modern Family” lead-in. And one week after rising opposite repeats, new 10 p.m. comedy ”Happy Endings” declined to a 1.7/ in 18-49 and 4.0 million viewers overall, with a second original episode at 10:30 p.m. earning a 1.4/4 in the demo and 3.3 million viewers overall.

NBC struggled from 8 to 10 p.m. with gameshow ”Minute to Win It” (1.0/3 in 18-49, 2.1 million viewers overall) but perked up at 10 p.m. with ”Law and Order: Special Victims Unit” (2.5/6 in 18-49, 8.3 million viewers overall), which led the broadcasters in 18-49 at 10 p.m. with its first original episode in a month.

At CW, ”America’s Next Top Model” (0.9/2 in 18-49, 1.9 million viewers overall) was down week to week and continues to track lower this season opposite ”American Idol.”

Preliminary 18-49 averages for the night: Fox, 5.4/15; CBS, 2.8/7; ABC, 2.1/6; NBC and Univision, 1.5/4; CW, 0.9/3.

In total viewers: Fox, 17.3 million; CBS, 10.7 million; ABC, 5.9 million; NBC, 5.0 million; Univision, 3.5 million; CW, 1.5 million.