Highlighted as usual by “American Idol,” Fox captured all four of its half-hours in key young-adult demos on its way to an easy victory Wednesday night, with CBS a solid second.

According to preliminary nationals from Nielsen, “American Idol” (projected 11.4 rating/30 share in adults 18-49, 27.7 million viewers overall) dominated from 9 to 9:32, and unscripted skein “Unanimous” (projected 5.4/14 in 18-49, 12.6 million viewers overall) finished the night for Fox a winner in key demo categories. “Bones” also prevailed at 8 for Fox (3.7/11 in 18-49, 10 million viewers overall).

Second-place CBS saw week-to-week increases for “Amazing Race 9” (3/9 in 18-49, 8.8 million viewers overall), “Criminal Minds” (3.7/10 in 18-49, 13.5 million viewers overall) and “CSI: NY” (4.8/13 in 18-49, 15.1 million viewers overall), with the latter leading its hour in all categories.

At ABC, the two-hour return of “Alias” averaged a ho-hum 2.7/8 in 18-49, 7.5 million viewers overall, growing with each half-hour. And “Invasion,” also back after a hiatus, settled for a soft 2.5/7 in 18-49 and 7 million total viewers, tying in the demo with NBC’s “Law & Order” (2.5/7 in 18-49, 7.8 million viewers overall).

The Peacock was again toast with night three of “Celebrity Cooking Showdown” (1.5/5 in 18-49, 4.9 million viewers overall) and weak new drama “Heist” (1.3/3 in 18-49, 3.9 million viewers overall).

UPN’s “America’s Next Top Model” (2.2/7 in 18-49, 4.5 million viewers overall) was up vs. the previous week, running second in the 8 o’clock hour among adults 18-34 (2.7/9).

Preliminary 18-49 averages for the night: Fox, 6.0/17; CBS, 3.8/11; ABC, 2.7/7; NBC, 1.8/5; UPN, 1.5/4; WB, .9/3.

In total viewers: Fox, 15.0 million; CBS, 12.5 million; ABC, 7.4 million; NBC, 5.5 million; UPN, 3.3 million; WB, 2.2 million